British police have arrested five men on suspicion of preparing a "terrorist" attack linked to the ongoing state visit of Pope Benedict XVI, Scotland Yard said today.

Police said the men were arrested early this morning "on suspicion of the commission, preparation or instigation of acts of terrorism" but the itinerary and policing arrangements for the Pope's visit remain unchanged.

The Pope was informed.

The five, said to be Algerian and aged between 26 and 50, were arrested under the Prevention of Terrorism Act at what police said was a business premises in central London at around 5:45am.

Searches at that property and houses in north and east London have not so far recovered any "hazardous items," Scotland Yard said.

"Following today's arrests the policing arrangements for the papal visit were reviewed and we are satisfied that our current policing plan remains appropriate," Scotland Yard said in a statement.

"The itinerary has not changed. There is no change to the UK threat level."

The Pope is spending today in London conducting a series of engagements on the second day of his state visit, including meeting Archbishop of Canterbury Rowan Williams and holding joint prayers with him at Westminster Abbey.

That service will be attended by figures reportedly set to include Britain's former prime ministers Margaret Thatcher, John Major, Tony Blair and Gordon Brown.