Abu Hamza was arrested on Monday along with two other men during a series of raids in the west London area by Scotland Yard's Anti-Terrorism branch.

Police have refused to disclose the identities of the two other men arrested, but they were released late on Thursday with Abu Hamza after questioning.

Ongoing investigation

The three men, aged 36, 39 and 40, were arrested under section 14 of the anti-terrorism act.

Under the legislation, people can be questioned for 48 hours. They can then be held for a further five days without being charged if the Home Secretary gives his approval.

Scotland Yard said the raids had been planned for some time and were part of an ongoing investigation.

Yemeni authorities, who requested Abu Hamza's arrest and extradition in January, have previously claimed the preacher is linked to terrorist activities in their nation.

Islamic preacher

Abu Hamza has denied the allegations.

His son, Mohammed Mustafa Kamel, is among 10 British and French citizens being tried in Yemen on charges of associating with armed groups, plotting murder and destruction, and possessing weapons.

All 10 have been linked to Islamic radicals who kidnapped 16 Westerners in December, four of whom died in a shootout when Yemeni security forces sought to rescue the hostages.

Authorities say Kamel confessed last month to forming an armed group in Yemen, but denied charges of weapons possession.

Hamza: Egyptian-born

All the other defendants have denied the charges.

Egyptian-born Hamza runs north London's Finsbury Park mosque and holds a UK passport. He has lived in London for 20 years.