On Friday afternoon pirates in control of the African Sanderling, a large cargo ship anchored off Somalia, were lazing in the sun waiting for their ransom money when the telephone on the bridge rang.

Muhammad, the man who answered, was rather polite for a pirate from a heavily armed gang that had seized the ship last month. “Plizz, excuse me,” he said, sounding more Cap’n Jack Sparrow than bloodthirsty Blackbeard. “Who are you?”

After The Sunday Times explained that it was calling to find out what was happening to the hijacked vessel, Muhammad was as helpful as his mangled English allowed.

“The ship, the crew and the captain is okay. No problem. Only problem, money.”

Have you demanded a ransom? “Yeah.”

How much? “First, $8m. Then they [the ship owners] make bargain, then reduce, then more bargain, $2m. Then they reduce it $1.2m. Last we said we need $2m.”

The ship, a 59,000-ton bulk carrier, was hijacked on October 15 with its crew of 21 Filipinos. What will the pirates do if they do not get a $2m ransom?

“Ah yeah,” said Muhammad. “If we miss the money, the ship and the crew will be missing.” As in missing, presumed dead.

The price of Somali piracy is rising fast. Yesterday The Sunday Times also contacted a young pirate aboard the Sirius Star supertanker, which was hijacked eight days ago 450 miles out in the ocean off the coast of Kenya. He said his gang is demanding a $17m ransom for the ship, which is carrying $100m worth of oil.

Another cutthroat with scruples, he said that the two British seamen among the 25 crew being held hostage were unharmed.

“The British are okay and we don’t have any problems with them,” said Muhammad Dashishle, 24. “All the people we captured with the ship are okay.”

The risk of a violent clash remains, however. An Islamic extremist group has threatened to seize the ship and Dashishle said the hijackers would fight any attack. “We have plenty of men to defeat them,” he said. “We are not afraid.”

As incidents of piracy proliferate and ransom demands soar, politicians and shipping lines around the world are growing more and more alarmed - and trade is being disrupted.

On Friday Maersk, the shipping company, ordered all its vulnerable vessels heading from the Arabian Gulf to Europe to avoid the Suez canal and follow the much longer route round the Cape of Good Hope. Governments fear that some ransom money may be ending up with Islamic extremists and terrorists may yet turn hijacked ships into weapons.

Until now many observers had assumed that pirates picked off vessels at random. Shipping and security experts, however, suspect they are increasingly using spies in ports such as Dubai to alert them to the best targets. It is also shockingly simple for anyone to track vessels online or to tune into ships’ AIS (automatic identification system) beacons. They transmit a ship’s exact position, size and cargo.

“It’s serious,” said Peter Hinchliffe, a director of the International Chamber of Shipping. “If the Sirius Star means pirates can attack deep in the ocean, warship patrols will not be enough. We need maritime patrol aircraft to protect shipping. We may even push to get the US navy to dedicate an aircraft carrier to the area.”

Any large cargo ship cruising at less than 15 knots, especially those low in the water, is easy prey for pirates in speedboats that can reach 20 knots. One of those captured in September was the bulk carrier Great Creation, which was released by pirates only last Wednesday.

“The pirates are just swarming around, even with all the warships,” said the captain, who spoke from his vessel as it was heading away from Somali waters and asked to be identified only as Ganesh.

“They come far out from land in the mother ship and when they see a target they launch speedboats. They threatened us with guns, RPGs. When they reached us, they fired to make us stop.”

The Great Creation was held for two months off the Somali coast. The captain and crew were confined to the ship’s accommodation block, although were otherwise well treated.

“They kept us inside but we weren’t locked up. As long as the owner is negotiating, they were well behaved,” said Ganesh. “But if the owners don’t cooperate, or if there is some problem with communication or there is a misunderstanding – then the situation could be very different. Otherwise, though, they won’t intentionally kill.”

As soon as it is clear that pirates are going to capture a ship, the crew activate the ship security alert system – in effect a panic button that transmits a warning to the owner.

“The guys that get on board hold a gun to the master’s head and say I am going to kill you unless you do as I say,” said Graeme Gibbon-Brooks of Dryad Maritime Intelligence Service. “The threat is always one of violence but it’s rarely carried out. You can’t ransom a burning hulk or a dead body.”

Instead, cat and mouse negotiations ensue, often lasting weeks. Several problems are arising with Somali pirates, according to Daren Dickson of Drum-Cussac, a security firm staffed by former special forces personnel: “The talks change over the weeks. Pirates may be fuelled by drink and drugs [many chew khat, a narcotic] and they forget what they agreed.” Pirates are also changing the way ransoms are delivered.

“The problem is the pirates don’t want the money in a bank in Somalia,” said Dickson. “It’s hard to access and the warlords get most of it.” So now some demand cash, air-dropped at sea or delivered at an offshore rendezvous.

“It increases the cost and risk,” said Dickson. “There have been attacks by other pirates on the way in [to deliver the ransom]. Air drop is a bit better; there are firms doing it out of Dubai and Mombasa.”

According to Dickson, the pirates generally abide by the rules. They sit on the stern of the ship, “divvying up the cash, then off they go”, setting the ship and crew free.

So far the casualties have been mainly attackers rather than merchant crews. In a recent clash the Royal Navy killed two suspected pirates and captured eight others, who were handed over to Kenyan authorities. Although two seafarers have died in pirate incidents, crews generally emerge physically unscathed.

French investigators who boarded a hijacked yacht in April even reported finding a pirates’ “good conduct guide” that forbade sexual assault.

The sheer number of attacks threatens serious disruption to shipping and more violent clashes. Piracy is the only growth industry in Somalia, one of the world’s poorest countries. Its unlikely epi-centre is the tiny fishing village of Eyl on the northeast coast in a region called Puntland. Less than a year ago it was mostly a jumble of crumbling, one-storey concrete buildings with tin roofs and wooden shacks on the beach. Bare-chested fishermen in knee-length sarongs used to set out on small wooden boats as their ancestors had for centuries.

Now goats wandering the dirt roads jostle with new SUVs as piracy brings a sudden influx of wealth - an estimated £15m this year. The lead pirates have near-celebrity status and are building palatial villas. Some members of Somalia’s ramshackle government, many of whom are natives of Puntland, are said to get payoffs.

“The pirates are making so much money,” said one source in Bossaso, the capital of Puntland. “They have taken second wives, they are all building new homes and buying new cars, like the latest Land Cruiser.”

They are also acquiring satellite phones and GPS navigation equipment to coordinate operations. One expert in neighbouring Kenya claims the pirates have become so sophisticated that they are backed by “investors”, who fund the upfront costs of hijackings in return for a share of the ransom.

What can be done to stop the pirates? Ship owners are reluctant to hire armed guards for fear of escalating confrontations. But nine days ago three former Royal Marines posted as private guards on a tanker in the Gulf of Aden demonstrated one weapon that may be useful.

When speedboats containing gunmen approached, the guards, working for a firm called Anti-Piracy Maritime Security Solutions, deployed “magnetic audio devices” that emit directed soundwaves of high intensity. Even at 600yd the noise is unbearable.

The former marines trained the devices on the speedboats, which kept their distance and after 10 minutes turned away to seek another target.

Shipping organisations also want the British government to make piracy on the high seas - beyond the UK’s territorial waters - a criminal offence that can be tried in Britain. At present UK naval forces cannot attack pirates, even if they are mounting a hijack, except in self-defence. Nor could captured pirates be tried in Britain.

A European Union taskforce of 10 ships, codenamed Atalanta, will set off for the region in December commanded by Rear-Admiral Phil Jones based at Northwood, north London.

Many shipping and security experts doubt it will be a cure. “The long-term answer to this is not more warships,” said Gibbon-Brooks. “The area is just so big. The answer is to sort out Somalia, which is a failed state. But that’s a five-year job, 10 years probably.”

Additional reporting: Richard Woods and Michael Smith