British anti-terror police have arrested five suspects during raids across Greater Manchester and near London's Heathrow airport, officials say.

The raids came on Monday as part of investigations into the alleged recruitment of terrorists to join training camps in Afghanistan, as Prime Minister Gordon Brown prepares to defend Britain's presence in the war-torn country in the face of growing public impatience with the unpopular mission.

The detainees include a 26-year-old man seized in a hotel near Heathrow and a 62-year-old preacher taken from his home in Bolton. Three others were also arrested in the operations over an alleged overseas threat, media reported.

A police official described the home sweeps as "low key," saying no armed officers were involved in the arrests.

"This is a complex and ongoing investigation, which has now reached the point where it was necessary to make arrests and speak to a number of people," AFP quoted Assistant Chief Constable Dave Thompson of Greater Manchester Police as saying.

"Protecting people both at home and abroad is our primary concern, which is why we take such steps," said Thompson, adding that the raids, starting at 4:00 a.m. (0400 GMT), were carried out by the North West Counter Terrorism Unit.

Britain reduced its national terror alert status in July from "severe" to "substantial," its lowest since 7/7 bomb attacks in London in 2005 that claimed 56 lives.

Brown is expected to vigorously defend Britain's mission in Afghanistan and Pakistan in his Monday night speech, warning that al-Qaeda was operating within UK soil.

He will underline the terrorist network as 'still' the biggest threat to Britain's national security, with a recruitment operation expanding throughout Africa, the Middle East, Western Europe and the UK.

ZHD/MMN