Egypt is concerned that the recent surge in piracy, highlighted by the hijacking of the Saudi supertanker Sirius Star loaded with $100m worth of crude oil last week, will prompt shipping companies to opt for safer routes that avoid the Canal.

That would mean longer, costlier trips around the southern tip of Africa but Odfjell SE, a big Norwegian shipping group, took that step on Tuesday, ordering its more than 90 tankers to take the longer route.

Danish shipper AP Moller-Maersk is also routing some of its 50 oil tankers around the Cape of Good Hope, while Norway's Frontline, which ferries much of the Middle East's oil to world markets, said it was considering a similar step.

Ransom demands

Earlier a spokesman for the pirates said they were demanding $25m for the return of the Sirius Star.

In depth

'Toxic waste' behind Somali piracy

Escaping Somalia's pirates

"We are demanding $25m from the Saudi owners of the tanker. We do not want long-term discussions to resolve the matter," Mohamed Said said.

"The Saudis have 10 days to comply, otherwise we will take action that could be disastrous."

The tanker was seized in the Indian Ocean some 800km off the coast of Kenya, and is now anchored off the Somali coast at Haradheere, roughly in the centre of the country's coastline.  It is the biggest vessel ever hijacked.

Somali pirates have now seized three ships off the coast of the Horn of Africa in the past three days.

A Greek tanker, a Thai fishing boat and a Hong Kong-registered vessel have also been captured despite a large international naval presence in the waters off Somalia.

According to the International Maritime Bureau the Thai fishing boat had 16 crew members on board.

Policing piracy

A coalition of warships from eight nations, as well as from Nato and the US Navy's 5th Fleet, is patrolling a critical zone in the Gulf of Aden where most of the hijackings have occurred.

Saudi Arabia and Egypt both have significant naval forces of about 18,000-20,000 personnel each, though it was unclear, even after Thursday's meeting in Egypt, whether the countries would deploy ships.

Other Arab countries in the region have smaller and less experienced navies.

 Pirates have anchored the Sirius Star off the coast of Somalia [AFP]
The INS Tabar, an Indian frigate, attacked a Somali pirate ship on Tuesday after coming under fire.

In Somalia, an impoverished country where public institutions have crumbled, many see piracy as the only profitable business.

The pirates are said to have built luxurious homes and propped up the economy in the semi-autonomous region of Puntland, where many of them are based.

Amid the anarchy and lawlessness in most parts of Somalia, northern coastal towns like Haradhere, Eyl and Bossaso, the so-called pirate economy is thriving, due to the money pouring in from pirate ransoms that have reached $30 million this year alone.

The seizure of the Sirius Star, prompted South Korea to look at sending military vessels to join US, French and Russian warships already operating in the area.

Jean Ping, The African Union's top diplomat, said on Thursday that the UN should send peacekeepers to Somalia to stop the fighting that is contributing to the growth of piracy.

But diplomats in the region say there is little hope of any speedy UN intervention in Somalia and Jaap de Hoop Scheffer, Nato's secretary-general, has said that the alliance would continue to patrol the seas but not get involved on land.

"Piracy is a very serious challenge and we have to fight it, but I think if you come to the part of these operations, for instance on land, then it is first and foremost up to the United Nations and not organisations like Nato to get deeply involved," he said during a visit to Ghana.

At least 13 vessels with more than 270 crew members are already being held by various pirate gangs. A Ukrainian-registered cargo ship carrying tanks and heavy weaponry remains anchored off the Somali coast.