The family of a British couple feared to have been seized by Somali pirates while sailing near the Seychelles said they are praying for their safety.
Paul and Rachel Chandler, aged 59 and 55, of Tunbridge Wells, Kent, sent a distress signal on Friday from the Indian Ocean near the Seychelles.
A possible yacht sighting, about 200 miles to the east of the Somali port of Haradheere, is being investigated.
Mr Chandler's sister Jill Marshment said it was "like a bad dream".
"[I] just can't believe it's happened but I'm afraid it does happen," she said.
"I'm sure they will come out of it alright... and they will do the best they can.
"They are quite strong people and we just hope and pray that they will be all right."
Mrs Marshment, from Worcestershire, added that the couple would have known about the risk from pirates beforehand and "being sensible people, would have taken that into account".
The European Union Naval Force Somalia said earlier it had located a yacht at about 1500 GMT, but did not want to give the family "false hope".
"One of the ship's helicopters involved in the investigation saw a yacht towing a pirate's skiff [a small boat]," said the spokesman.
"As light was fading, it was impossible to identify it. It was the first yacht we've seen. It's in the area where we've been looking for this yacht.
"I don't want to give the family false hope. We are treating the sighting very seriously. There will be at least two European Union Naval Force ships going to investigate."
Paul Chandler's sister Jill Marshment: "It's like a bad dream"
Mr and Mrs Chandler were heading for Tanzania in their yacht the Lynn Rival.
A pirate called Hassan told Reuters news agency: "The British couple are in our hands now. We captured them as they were touring in the Indian Ocean."
The two captives were healthy and ransom demands would follow, he added.
A Foreign and Commonwealth Office spokeswoman said it could not confirm whether pirates were involved.
Britain's Maritime and Coastguard Agency said the couple's distress beacon was activated at 2300 BST on Friday.
They were on a 150 nautical-mile passage south-west to the Amirante Islands, en route to Tanzania when they used the Emergency Position Indicating Radio Beacon.
The route would have taken the couple near Somali waters which are notorious for pirate attacks on ships and smaller boats.
Paul and Rachel Chandler were on a 150 nautical-mile passage south-west to the Amirante Islands