IN THE EARLY hours of March 15, British police raided the home of Abu Hamza al-Masri, the London-based imam, and arrested him along with two other men for questioning under the Prevention of Terrorism Act. After three days all were released on condition that they report to the police again on May 18.

It is believed that the police investigation covers Abu Hamza's activities in Britain - where his Supporters of Shariah organisation has advertised "military training" - and also events in Yemen. The Yemeni authorities claim that Abu Hamza sent 10 of his group's adherents from Britain (including his son and stepson) to bomb British and American targets in Aden. In addition, Abu Hamza admits to having links with the Islamic Army of Aden-Abyan which kidnapped 16 western tourists in Yemen last December.

The two others arrested in London, although not officially named, are understood to be Yassir al-Sirri, an Egyptian asylum-seeker, and a man known as Frank Ben Ilias.

There was speculation last week that Abu Hamza's arrest might be part of a secret understanding between the British and Yemeni governments. Yemen has been seeking his extradition (though there is no extradition treaty) and the suggestion is that British action against Abu Hamza will secure lenient treatment for the "bomb plot" Britons on trial in Aden. There is, however, no certainty at this stage that Abu Hamza will be charged with any offence.

On March 20 the Aden trial, which had been suspended until after the hajj season, was unexpectedly reconvened while several of the defence lawyers were on holiday. The Yemeni authorities say they want to clear a backlog of cases.

At an earlier court session, defence lawyers were taken by surprise when the prosecution produced two videos seized at a villa in Aden which was rented by Abu Hamza's stepson, Muhsin Ghalain. One showed four of the accused holding automatic weapons during "military training" in Albania last August. Ghailan told the court he had made the video as a "souvenir" of their trip. The second video showed one of the defendants with Abu Hamza.

The defence team complained that they had not been informed of the videos beforehand, and so had no opportunity to assess them or to take instructions from their clients. They suggested that the tapes were inadmissible because they provided no evidence of crimes committed in Yemen.

A separate bomb trial in Aden - the fourth in the last two years - ended on March 17 with one man sentenced to death and 10 others to prison terms ranging from two to 10 years. Two were acquitted. They were accused of an attack in July last yea, which killed five people.