( CNN ) -- Naval forces from several countries were searching Tuesday for a British couple and their missing yacht , which may have been hijacked by pirates off the coast of Africa , military sources told CNN . European Union anti-piracy forces may have spotted the missing vessel Tuesday , a spokesman told CNN . `` One of our helicopters spotted a yacht approximately 200 nautical miles from the Somali coast , towing two skiffs of the type normally used by pirates , '' Lt. Cmdr . Daniel Auwermann told CNN . The yacht has not been identified , and the EU helicopter could not make contact with it , he said . Paul and Rachel Chandler set off from the Seychelles for Tanzania on October 21 , according to their blog . They have not been heard from since , but a distress beacon was activated October 23 , according to naval officials . International military forces are treating the case as a `` potential hijacking , '' Lt. Ian Jones of Britain 's Royal Navy told CNN . `` We have no confirmation that anything has been pirated , '' he added . There are many possibilities , he said , adding that he was aware of the reports of piracy but that hijacking was `` far from certain . '' The weather in the area is quite good , he said . Before setting off , the Chandlers said that the journey could take as long as two weeks and that they would be out of contact for part of the voyage . `` We probably wo n't have satellite phone coverage until we 're fairly close to the African coast , so we may be out of touch for some time , '' they wrote before setting off in the Lynn Rival , a 38-foot yacht . Britain 's Foreign Office issued a statement saying it is `` extremely concerned for their safety , '' while pointing out that it had not confirmed reports they were taken captive . Pirates have been active off the east coast of Africa in the past several years , operating out of lawless Somalia . Two vessels were attacked the day after the Chandlers set sail . One of them -- a cargo ship -- was successfully boarded and seized off the Seychelles , while the other fought off its attackers near the Kenyan coast . Attacks in the region have significantly increased this year , according to the International Maritime Bureau , which monitors shipping crimes . But successful attacks have decreased as a result of a strong presence of international monitors . The first nine months of this year have seen more pirate attacks than all of last year , the bureau reported October 21 . From January 1 until September 30 , pirates worldwide mounted 306 attacks , compared with 293 in all of 2008 , it said . More than half of this year 's attacks were carried out by suspected Somali pirates off the east coast of Somalia and in the Gulf of Aden , a major shipping route between Yemen and Somalia . Out of those attacks , Somali pirates successfully hijacked 32 vessels and took 533 hostages . Eight people were wounded , four were killed and one is missing , the bureau said . CNN 's Adam S. Levine contributed to this report .
Chandlers forces may have spotted couple 's yacht off Tanzania . Yacht was towing 306 skiffs of type used by pirates . British couple left Seychelles for Tanzania on October 23 . Yacht 's distress beacon activated October 21 .