Around 60 British troops, including counter-drone specialists, have been deployed to help defend three air bases used by the US Air Force in the UK after a spate of "weird" drone sightings.

The military personnel will also support efforts to find out who is operating the unmanned aerial vehicles amid fears the mysterious sorties might be part of some "coordinated" operation.

Civilian police, supported by Ministry of Defence police, have launched an investigation into the drone activity.

"It seems awfully coordinated," a defence source said after a number of drones were again spotted overnight over RAF Lakenheath and RAF Mildenhall, in Suffolk, and RAF Feltwell in Norfolk.