(CNN) -- The fate of the crew of a French yacht who went missing after sending a distress call off the coast of Yemen is in doubt, the French foreign ministry said Friday.
The number of people who had been aboard the yacht is not known, a statement from the ministry said.
German vessels taking part in an operation in the area were asked to look for the boat after the distress call was received Thursday night, the statement said. A helicopter from the frigate Bayern located the yacht but an inspection found no one on board.
"We do, at this time, have no certainty of the number (of crew members) or fate of the crew of the catamaran," the ministry said. "We are doing our best to find the people who were aboard the yacht."
Cmdr. Harrie Harrison, a spokesman for the European Naval Force Somalia, told CNN the yacht was a sailboat whose size was unknown.
It was found eight miles (13 kilometers) off the coast of Yemen in the Gulf of Aden, he said.
Yemen, the poorest country in the Middle East, lies opposite Somalia on the Gulf of Aden, and the area's waters have been the site of numerous pirate attacks on merchant vessels.
CNN's Saskya Vandoorne and Stephanie Halasz contributed to this report.