Benedict's UK visit was marked by repeated expressions of remorse over the paedophile priest crisis [AFP]

A statement from Scotland Yard says British police have freed six men without charge after they were arrested over an alleged plot to launch an attack during Pope Benedict XVI's state visit.

Counter-terrorism police raided a cleaning depot in London early on Friday to arrest five men, aged between 26 and 50, "on suspicion of the commission, preparation or instigation of acts of terrorism", police said.

A sixth man was detained later on Friday.

In its statement, released on Sunday, Scotland Yard said: "Six men who were arrested under the Terrorism Act 2000 on Friday, were all released without charge late on Saturday night and early this morning."

The men were street cleaners employed in the Westminster district of London, where Benedict spent much of Friday and Saturday, the local authority confirmed.

Vatican reaction

The Vatican on Saturday played down the threat after the arrests of the men.

"We never attributed much importance to these arrests," Federico Lombardi, the Vatican spokesman, said on Saturday.

Benedict was "very calm", he said, and the four-day trip - the first ever state visit by a pope to Britain - was "taking place smoothly".

Britain's Sunday Mirror tabloid quoted a police source as saying that the men were arrested after they were overheard joking in a staff canteen about blowing up the pope with a rocket-propelled grenade.

Reports said the men were all of North African origin but there was no confirmation from police.

Expressions of remorse

The first papal trip to mainly Anglican Britain since John Paul II visited in 1982 has been marked by repeated expressions of remorse over the paedophile priest crisis engulfing the Roman Catholic church.

Benedict met on Saturday in London five victims of sexual abuse by clergy - four women and a man - and expressed his "shame" and "deep sorrow" for their suffering.

Thousands of protesters opposed to Benedict's stance on clerical abuse, gay rights, contraception and a host of other issues marched through central London on Saturday.

They were far outnumbered, however, by the 85,000 pilgrims who attended a huge open-air prayer vigil led by him in London's Hyde Park.

Benecict is set to fly from London to Birmingham on Sunday for the beatification mass of John Henry Newman, a convert from Anglicanism to Catholicism, before returning to Rome.