POLICE have erected a no-fly zone over the site of the collapsed tunnel amid structural concerns.

Network Rail is taking advice from structural engineers andhealth and safety executives to determine the stability of the site and the cause of the collapse.

On Friday, July 1, the British Transport Police erected a no-fly zone over the area. Chief Inspector Willy Baker, of the British Transport Police said: "There's a lot of dust and the ground. We were afraid the downdraft from aircrafts andhelicopters would disturb the site and possibly destabilise it further, causing another collapse."