A female security guard has been arrested near the Olympic Stadium on suspicion of possessing explosives and class A drugs.

The woman, a 40-year-old dog handler, was detained after her vehicle was searched by police in a car park off Pudding Mill Lane, Stratford, on Tuesday evening, it has been revealed.

Scotland Yard said the arrest was made by Olympic site support unit (OSSU) officers after a tip-off.

They said they do not believe the incident is related to terrorism and said the site’s safety had not been at risk.

The woman is being questioned at a police station in East London.

Police said another car had been stopped and searched by the OSSU on the M11 on Tuesday and yesterday, but the driver had not been arrested.

Searches were also carried out at residential addresses in Kent and London.

It is understood a very small amount of a substance recovered by police was being forensically examined.

The woman is employed by private security firm G4S.

A spokesman for the Olympic Delivery Authority said: “There are robust measures to ensure the safety and security of the Olympic Park.

“We are working with the police in their investigation. At no point has the safety and security of the Olympic Park been put at risk.”

The arrest came on the day building work was completed at the �486m Olympic Stadium.

A spokesman for G4S said: “Our canine services team is licensed to hold small samples of explosives for training purposes and are required to undertake rigorous training and follow strict operational processes. G4S take breach of operational processes very seriously and are assisting the police with their inquiries in relation to this incident.”