“The British couple are in our hands now. We captured them as they were touring in the Indian Ocean,” a pirate called Hassan told Reuters. He said the two captives were healthy and ransom demands would follow.

A Seychelles government source said an emergency distress signal was picked up by the British coastguard after Paul and Rachel Chandler headed out into waters notorious for pirate attacks on 22 October.

“We are currently in touch with the family in the UK and the Seychelles coastguard who continues to monitor the situation and has conducted a search of the area,” Matthew Forbes, British High Commissioner to the Seychelles, told Reuters.

A final message on the couple’s blog posted at dawn on Friday morning read: “Please ring Sarah”. There has been no communication with the 38-foot yacht, Lynn Rival, since then.

A diplomatic source said the Seychelles coastguard had launched a search operation on Friday but there had been no confirmed sighting of the vessel.

Maritime sources were unable to confirm the location of the vessel at the time the emergency beacon was activated.

A sailors’ forum on the Internet quoted the US National Intelligence Agency as saying the distress signal was picked up at 0133 GMT on Friday and that the vessel was 111 km west of Victoria, the Seychelles’ capital.

This is the latest incident in a spate of recent pirate activity. Here is a list of ships under the control of Somali pirates:

• WIN FAR 161: Taiwanese tuna boat, seized on April 6, 2009.

• ARIANA: Seized on May 2, 2009. Ariana was seized north of Madagascar en route to the Middle East from Brazil. The 24 Ukrainian crew were said to be unhurt. The ship, flying a Maltese flag, belongs to All Oceans shipping in Greece.

• CHARELLE: Seized on June 12, 2009. The 2800-tonne cargo ship carrying about nine crew was attacked south of Oman.

• ALAKRANA: Seized on Oct. 2, 2009. The 3716-tonne fishing vessel has a crew of 36 and a home port in the Spanish Basque Country. The Seychelles coastguard said the ship was seized 400 nautical miles northwest of Mahe. The vessel had previously escaped an attempted hijack on Sept. 4.

• KOTA WAJAR: Seized on Oct. 15, 2009. The 24,637-tonne container ship, seized 300 nautical miles north of Seychelles, was heading for the Kenyan port of Mombasa from Singapore. It had 21 crew on board.

• DE XIN HAI: Seized on Oct. 19, 2009. The Chinese bulk carrier carried about 76000 tonnes of coal and there were 25 Chinese crew aboard when it was hijacked in the Indian Ocean 550 nautical miles northeast of the Seychelles and 700 nautical miles off the east coast of Somalia. The vessel is owned by the Qingdao Ocean Shipping Co.

• AL KHALIQ: Seized on Oct. 22, 2009. The Panamanian-registered ship carried 26 crew, 24 of whom are Indian. The ship is owned and operated by SNP Shipping of Mumbai. The 1984-built, 38305 dwt bulk carrier was seized around 180 nautical miles west of Seychelles.

• LYNN RIVAL: Seized Oct. 2009. A British couple, Paul and Rachel Chandler, were sailing to the east African country of Tanzania when they were seized on their 38-foot yacht.