Officials in Yemen are conducting extensive searches in the area where the bodies of three foreigners were found in an attempt to trace six others - including a British man - feared kidnapped.
Shepherds found the mutilated bodies of two German nurses and a South Korean teacher who had been kidnapped while on a picnic in Saada, an area known to be a hideout for al Qaida.
Experts said the killings bore the hallmarks not of local tribesmen but of jihadist militants who had returned home after fighting in conflicts in Afghanistan, Iraq and elsewhere.
The dead women disappeared in the remote northern province on an outing with the six others, who also include a German doctor, his wife and their three young children, and their whereabouts are unknown.
Yemeni authorities announced a state of high alert in the area and said they are carrying out investigations into what has happened.
All those involved worked for World Wide Services Foundation, a Dutch aid group helping with medical care in the province.
The government has blamed the kidnapping on a Shiite rebel group that has been leading an uprising in the province for the past several years, but the group denied it had anything to do with it.
Initially, Yemeni security officials had reported all nine were killed, but the government later said six are still missing.
The Foreign Office has said it is "very concerned" about the missing Briton, who is believed to be an engineer.
