A Briton, an American and a South African were among hostages Yemeni forces tried to free from al-Qaeda this week.
On Monday night, Yemeni troops raided a cave in the remote Hajr as-Say’ar district in the eastern province of Hadramout during an operation that a US defence official said also involved US special forces.
They rescued six Yemenis, a Saudi and an Ethiopian, and killed seven al-Qaeda kidnappers.
On Wednesday, the defence ministry’s website quoted a soldier who had taken part in the rescue. He said that an American, a Briton and a South African held in the cave had been moved elsewhere two days earlier.
While al-Qaeda-linked gunmen in Yemen are known to be holding foreign hostages, an American had not previously been reported among them.
The identity of the hostages is not known. But South Africa has said one of its nationals, Pierre Korkie, was being held in the country after he was kidnapped in 2013.