LONDON, England (AP) — Nearly 100 people have been arrested for selling fake tickets and bogus hotel rooms ahead of the London Olympics.

With some six months to go before Britain’s largest-ever planned security operation, Home Secretary Theresa May said police had arrested 97 people in scams involving tickets, fake Olympic websites and nonexistent hotel rooms.

The demand for tickets and hotels in London during the July 27-August 12 games has been huge — some rooms are going for more than 600 pounds per night (nearly $1,000).

“Police are sending a very clear message that we’re not going to tolerate intrusions by organised criminals into the Olympic Games,” May said during a speech at the Royal United Services Institute in London, a British security think-tank.

London police said the tickets involved in the scam were phony.

But the threat most on the minds of organisers is terrorism — Britain was the first western European country to be targeted by al-Qaeda-inspired suicide bombers who launched attacks on London’s transit system in 2005, killing 52 people the day after the city won the 2012 Olympics bid.

Security officials are also haunted by the attack at the 1972 Olympics in Munich that killed 11 Israeli athletes and coaches.

Intelligence officials say there is nothing to suggest a specific and credible terror threat to the London Games, yet the threat level will rise to “severe”.

Britain’s police, the domestic spy agency MI5, the foreign intelligence agency MI6, government communications surveillance units and the military will all help secure the Olympics against possible threats. In addition, international law enforcement and policing agencies like Interpol and the FBI will help British authorities. More than 20,000 security guards are also being hired for extra protection.

“Many of our resources will be dedicated to counterterrorism operations,” said Commander Bob Broadhurst, in charge of operational planning for Scotland Yard, who said one concern is being able to patrol parallel or unplanned events around the Olympics, such as concerts and other celebrations.

Although Broadhurst said protests would be allowed during the games, May said protest camps around key sites would be prohibited.

Security teams have already started testing their preparedness.

Two weeks ago, it was disclosed that British police testing security protocols had earlier managed to smuggle a fake bomb into Olympic Park. Last week, a police officer reportedly left documents about security arrangements for the London Olympics on a train.

Officials said those documents were not sensitive and such test-runs are part of the training.

Training events around London have been visible for months — last week, British police joined up with the military to practise boarding suspect vessels on the River Thames and to stop others by using equipment that entangles their propellers.