Police are hunting two men after a terrifying knifepoint robbery at Marylebone station.

One man threatened threatened security van staff with a knife on the station forecourt, before taking what is believed to be an empty cash box, on Monday at around 12.30pm.

He rode off on a motorbike with a second man, who was waiting at the junction of Melcombe Place and Boston Place. The bike, which had been reported stolen on Sunday, was later found abandoned nearby.

Investigating officer from the British Transport Police (BTP) Detective Sergeant Alan Bardsley said no one was hurt during the robbbery, but a cyclist in his late 20s received minor injuries when was hit on the shoulder as the robbers travelled down Harewood Row.

CCTV footage released by police shows the knifeman was in his late 20s, clean shaven, of medium build and had short spiked-up hair. He was wearing a black jacket and trousers. The second man was white, and wearing a black jacket and black crash helmet.

DS Bardsley said: "This happened at a time when there would have been many people at or near to where the robbery took place. We would like to speak to anyone who may have seen the purple and grey Suzuki motorcycle in the 24 hours preceding the incident to come forward and assist us with our enquiries."

Anyone with information should contact BTP on 0800 405040 and quote reference B7 02/09/08 or call Crime Stoppers anonymously on 0800 555 111.