THE investigation into the Salisbury nerve agent attack could take months, a senior police officer has said.

Assistant Commissioner for Counter Terrorism at the Metropolitan Police Neil Basu told the BBC: "This is going to be frustrating for people. It is going to take weeks, possibly months to do this.

"We are up to around 400 statements. We have got more statements to take. We are nearly at 800 exhibits and 4,000 hours of closed circuit television footage."

Asked if the police focus was on the car involved in the case, Mr Basu said: "Our focus is on the movements of the Skripals, so we are open-minded and will follow that evidence wherever it takes us.

And he praised the "very brave" scientists and forensics officers for their "painstaking" work, and the "remarkably stoic" people of Salisbury for their support..

Mr Basu said detectives would release CCTV footage "as and when we get an operational update the public can help us with".