A running club sparked a terror incident after it used white powder to mark out the route of a five-mile circuit.

Police cordoned off part of the local Tuesday Market Place in King’s Lynn, Norfolk, after a member of the public saw a man and a woman leaving plies of a white powder at different points in the area last Saturday morning.

Norfolk Fire Service hazardous material specialists were sent to investigate amid fears of a possible chemical terror attack where they realised the mystery substance was corn starch flour.

Officers said they were looking for a man on a bicycle and a woman in a red top when members of the Norfolk Hash House Harriers running club came forward to say they had put out the flour.

Norfolk Police had feared that the powder could be a Novichok-style substance similar to the nerve agent used in March to poison Sergei Skripal, 66, and his daughter, Yulia, 33, in Salisbury, Wiltshire.