LONDON - Seven men have been arrested on suspicion of terrorist offences in Britain after a routine vehicle search in northern England turned up firearms and weapons, police said Friday.

The arrests, which took place earlier this week, were announced one day after officers in London detained six other terror suspects using stun guns and smoke grenades in early-morning swoops, including one on a home close to London's Olympic Park.

Police insist that the 13 arrests in recent days did not involve threats to the Olympics set to begin in three weeks, but the counter-terror sweeps — and a false alarm Thursday that involved a bus filled with passengers — have raised anxiety in the run-up to the games.

The arrests came as transport officials established special "games lanes" on key London roads that will be used only by Olympic athletes, officials and VIPs, adding to the sense that the start of the long-awaited Olympics is just around the corner.

Police on Friday said there was nothing to suggest that the newly announced arrests were linked to the London raids a day earlier. They said the arrests came after a car was stopped on the southbound side of the M1 highway in South Yorkshire on June 30 and impounded for not having insurance.

Two unloaded, non-automatic guns and a small amount of ammunition were later found hidden in the vehicle along with "offensive weapons and other material," which prompted police to trace and arrest the driver, passenger and other suspects, according to West Midlands Police.

Prime Minister David Cameron's spokesman Steve Field insisted there was no sense of alarm at the spate of arrests so close to the start of the Summer Games.

"We have been looking at the issue of security at the Olympics for some time and we have robust plans in place," he told reporters.

Police said three of the men were arrested Tuesday, three on Wednesday and one on Thursday. Six of them are in their twenties and from the West Midlands, while one is in his 40s and from West Yorkshire.

The men have been arrested on suspicion of preparing or instigating acts of terrorism. They were being questioned by officers and their residences were searched.

The items found in the vehicle were undergoing forensic testing.

Britain's terror level is currently ranked as substantial — the third highest point on a five-point scale — and means an attack is a strong possibility. Intelligence officials say there has been an expected increase in chatter among extremist groups ahead of the Olympics, but there are still no specific or credible threats targeting the games.

___

Associated Press writer David Stringer contributed to this report.

___ Cassandra Vinograd can be reached at http://twitter.com/CassVinograd

News from © The Associated Press, 2012