The four British detectives who are in Yemen to investigate the deaths last week of three kidnapped British tourists are expected to head for the port of Aden today.

A Western diplomat said they planned to leave the capital, Sanaa, to get closer to the scene of the shoot-out between government troops and the tourists' captors.

But he said they were still waiting for permission from the Yemeni authorities.

The British detectives have been meeting Yemeni and American officials in Sanaa since arriving on Friday.

One of them told the BBC that as this was what he called a covert operation, very few details, if any, could be given out to the public.