Teams of British and American detectives have arrived in Yemen to help the inquiry into the recent abduction of western hostages.

The kidnapping ended on Tuesday with an ill-fated rescue operation, during which four tourists three Britons and an Australian were killed.

The investigators want to learn more about the identity of the kidnappers - who call themselves Islamic Jihad - and whether they have links with similar organisations around the world.

The British Foreign Office has told the Yemeni authorities that it expects them to provide more information than they have been giving until now.

One survivor says he was asked to change his account of the rescue, to remove any suspicion that Yemeni troops were responsible for his wife's death.