Drones are to be used in the aftermath of Salisbury-style chemical weapons attacks to keep the emergency services safe from contamination.

As accusations and denials continue to fly between London and Moscow following of the poisoning of Sergei and Yulia Skripal in March, military scientists from Porton Down have tested a fleet of drones and robots which can check for chemical and biological agents.

Among the hardware under examination by scientists, soldiers and police officers were a robot that can climb stairs and ‘read’ hazardous chemical signs, a nano-drone the size of a bar of soap which can detect gas, and the hybrid air-and-ground “Snake Eyes” drone manufactured by a private lab in Milton Keynes.

Snake Eyes is small enough to be posted through a letterbox but can transmit a 3D image of its surroundings back to its operator, and check the scene for traces of chemical elements, according to the MoD.