LONDON (Reuters) - Somali pirates have been using Yemen's remote Horn of Africa island of Socotra as a refuelling hub enabling their attack craft to stay restocked for longer periods at sea and pose a greater hazard to shipping, maritime sources say.
Despite an international naval presence in the region, seaborne gangs have been exploiting political turmoil in Yemen to pick up fuel, and possibly other supplies including food, sources told Reuters.
"Socotra has been used for months if not longer," said Michael Frodl, with C-LEVEL maritime risk consultancy and an adviser to Lloyd's of London underwriters, citing intelligence reports he was privy to.
"It is perhaps the most important refuelling hub for hijacked merchant vessels used as motherships, especially those operating between the Gulf of Aden and India's western waters, mainly off Oman and increasingly closer to the Strait of Hormuz."
"A hijacked merchant vessel, unlike a hijacked dhow, has a voracious thirst for fuel and needs a very well stocked refuelling station," Frodl said.
A Yemen government official said authorities around a month ago had captured 20 people believed to be pirates on the island and handed them over to authorities in Yemen's nearby southern port city of al-Mukalla on the mainland.
A source said separately the 20 people had been on a regular commercial ship, but added that 16 Somali pirates were taken into custody in recent days and were being detained on Socotra.
"There was a lot of piracy north of Socotra during the north east monsoon and it is likely they have been using the island," the source said. "Pirates use the beaches on the mainland not too far from Mukalla to collect fuel, and presumably other equipment."
The International Maritime Bureau (IMB.L) watchdog said the pirate support systems had to be promptly stopped.
"Socotra is strategically located because it is right up there against the Gulf of Aden and also along the eastern seaboard of Yemen," said IMB director Pottengal Mukundan.
"If it is true that the pirates are using Socotra, then it is an extremely disturbing development and it requires immediate investigation."
Somali gangs, who are making millions of dollars in ransoms, are becoming increasingly violent, and are able to stay out at sea for long periods and in all weather conditions using captured merchant vessels as mother ships. The crisis is costing world trade billions of dollars a year.
The group of four islands in the isolated archipelago, the largest of which is Socotra, are located due east of the Horn of Africa in the Arabian Sea, and have been administered from Yemen for much of the last two centuries.
"Socotra has been a favourite stomping ground for pirates for centuries as both Marco Polo and the great 14th century Islamic scholar and traveller Ibn Battuta attest," said J. Peter Pham, with U.S. think tank the Atlantic Council.
"A credible amount of evidence has emerged in recent years that Somali pirates have certainly taken advantage of jurisdictional issues to operate in and out of the Socotra archipelago with at least the tacit connivance of at least some Yemeni authorities."
A maritime security source said there were transactions taking place between dhows in the Socotra archipelago as well.
"In addition to fuel, these exchanges involve arms, most of which are then shipped to Puntland for distribution either to pirates or to various armed factions," the source said.
Pirates conducted several attacks in May in the Arabian Sea and some strikes in June. Maritime officials say the islands will become more difficult to reach in smaller ships until October because of wind, sea and swell conditions.
Yemen's military is believed to have a base on Socotra, maritime sources said. "If the military wanted to supply mother ships with fuel from Socotra they could. Corruption in Yemen is rife," another maritime source said.
NATO said it had ships in the Horn of Africa and Gulf of Aden since March 2009 and the presence of NATO warships and other nations' navies had resulted in a significant reduction in pirate attacks in the Gulf of Aden over the past two years.
"We are not complacent and understand there is still much work to be done," a NATO spokeswoman said.
"As Yemen forms the northern coast of the Gulf of Aden and is only 200 miles from Somalia, it is feasible that the pirates could use Yemeni ports for supplies. However, we have no evidence to suggest that this is happening. Similarly with Socotra, there is no evidence to suggest it is used as a pirate hub."
Yemen, the Arab world's poorest country, has been paralysed by six months of mass protests against President Ali Abdullah Saleh's three-decade rule.
After surviving an assassination attempt last month, Saleh went to Saudi Arabia for treatment. The Arabian Peninsula country has descended into violence with militants suspected of ties to al Qaeda seizing two cities.
"In the 1990s, before there was much by way of Somali piracy, the real threat in the region was from Yemeni pirates," the Atlantic Council's Pham said.
"While they were largely put out of business by more aggressive Somali pirates as well as governmental action, in the absence of the latter, the threat could re-emerge as well."
Alan Fraser, Middle East analyst with security firm AKE, said it was unlikely that Somali pirates would have any real interest in carrying out major activities on Yemen's mainland even if the situation deteriorated.
"Tribal codes and religious values are more conservative in Yemen than in Somalia so piracy is not likely to take off in the same way," he said.
Additional reporting by Mohammed Mokhashaf in Aden