Five men have been arrested over a potential threat to the Pope, Sky News can reveal.
Armed counter-terror officers swooped on a business premises in central London in the early hours of the morning.
The suspects, who are aged 26, 27, 36, 40 and 50, are being held and questioned under the Terrorism Act 2000.
Sky News crime correspondent Martin Brunt said: “The Pope’s itinerary continues today.
“His security arrangements have been reviewed and nothing has changed in terms of the level of protection around him.
“I was at a briefing last week around the whole issue of the Pope’s security and the point was made then that there was no known threat or intelligence to suggest a plot against the Pope.
“What the police are dealing with today is something that has cropped up in the last 24 hours.”
The business where the arrests were made is now being searched, as well as homes in north and east London.
Details of the alleged plot are so far scarce, but Sky sources can confirm that it did not originate overseas.
However, Sky News understands the suspects are of Arab origin.
A spokesman for Scotland Yard said: “Initial searches have not uncovered any hazardous items.
“Today’s arrests were made after police received information. Following initial inquiries by detectives, a decision was made to arrest the five men.
“Following today’s arrests the policing arrangements for the Papal visit were reviewed and we are satisfied that our current policing plan remains appropriate.
“The itinerary has not changed. There is no change to the UK threat level.”