Police said they had arrested five men today in early morning raids in northwest England.
Police said the suspects - aged 21, 26, 27, 52 and 62 - were detained under the Terrorism Act 2000 after raids at homes in Manchester and Bolton, and at a hotel near London's Heathrow Airport. The properties were now being searched.
In April, police carried out raids across northwest England in an operation against what Prime Minister Gordon Brown described at the time as a "very big terrorist plot".
Those raids had to be brought forward after the then-top counter-terrorism officer was photographed carrying a document relating to the operation, and 12 men who had been arrested were later released without charge.
Mr Brown will use a speech later today to warn of the threat posed by al-Qaeda to justify military action in Afghanistan, saying the militant group had an extensive recruitment network across the world including in Britain.
"I vigorously defend our action in Afghanistan and Pakistan because al-Qaeda is today the biggest source of threat to our national security - and to the security of people's lives in Britain," he will tell the annual London Lord Mayor's Banquet, according to excerpts of the speech released in advance.
Reuters