SAS SNIPERS GUARD ATHLETES

ISOBEL DICKINSON which killed five people. The starting and finishing lines as well as congested points such as Tower Bridge are said to be the biggest weaknesses on the course. Around 40,000 runners will take part, including celebrities and sports personalities. Security sources said the huge numbers involved made it a “nightmare” scenario. An insider told the Daily Star Sunday: “A lone wolf attack is at the top of the police and MI5’s security threats. “As well as the runners there will be thousands of people gathering across London to cheer them on. “It is a security nightmare which is almost impossible to police. “Most of the roads are going to be sealed off but there could be some places where vehicles could smash through barriers.

“These will be guarded by snipers with high-powered rifles which can stop a car in its tracks.”

Security teams will use facial recognition cameras to scan crowds for known extremists. Our source added: “There will also be police officers trained to spot suspicious activity monitoring banks of remote-controlled TV screens.”

In 2013, three people were killed and more than 260 injured when two brothers set off bombs by remote control at the Boston Marathon.

Security teams this week carried out checks along the London route.

The insider added: “Various electronic counter-measures will be in play to prevent remote-controlled bombs being used.” Anti-terror expert Neil Doyle said the use of improvised explosive devices – like the one used in the St Petersburg metro bomb attack earlier this month – were a concern.

He said: “Instructions for making bombs of the type used in the Russia attack are in circulation, so the risk to the London Marathon is maybe somewhat greater than it has been in previous years.”