Detectives are searching six addresses in Birmingham following the arrest of a third man suspected of involvement in terrorism, Scotland Yard have confirmed.
The 33-year-old man was detained yesterday by officers from the Metropolitan Police Anti-Terrorism unit and is being held at an undisclosed police station in the West Midlands.
A Scotland Yard spokesman said police were searching three homes and three business premises, but confirmed detectives have not so far recovered any weapons or explosives. The spokesman said the arrest was not linked to other operations in Gloucestershire and Lancashire.
Police searched three houses in Gloucester today as they questioned a suspected would-be suicide bomber whom the government says may be linked to al-Qaeda. They have also carried out a second investigation of a nearby house where they found explosives during an initial raid yesterday.
In London, they continued to question a 24-year-old Muslim man arrested during that raid.
Police, who can hold the suspect for up to seven days under sweeping anti-terror laws passed three years ago, declined to comment on the man's suspected intentions.
But newspapers speculated he may have been planning the country's first suicide attack on a soft target such as a sports stadium or the royal family.
One newspaper said the suspect had a shoe bomb similar to the one which Islamic convert Richard Reid planned to use to bring down a transatlantic airliner. British-born Reid was jailed for life in the United States in January.
Scotland Yard declined comment on the alleged link with Reid and in Manchester, where a man was arrested yesterday in an unrelated anti-terror swoop, police denied rumours of a specific plot to target Manchester United's Old Trafford soccer stadium.
"There has recently been speculation about a specific terrorist threat to football clubs and their grounds in the Greater Manchester area," Assistant Chief Constable Dave Whatton said in a statement. "This is not the case...we are not aware of any specific targets."
Home Secretary David Blunkett stressed the importance of the raids in Gloucester - part of a broader security operation that included searches in the northern city of Blackburn.
"Obviously the use of the Terrorism Act 2000 indicates the extent of the concern of the security and counter-terrorism branch of the Metropolitan police," he said.