Staff have been threatened in two separate knife raids at convenience stores in Medway within minutes of each other.

Detectives investigating the unsuccessful robberies in Chatham and Gillingham have today linked the cases and released CCTV images in an appeal for witnesses.

The hooded and masked offenders are believed to have been armed with large knives in the terrifying raids last night.

Kent Police were called to the first attempted robbery at the Co-op in Albert Road, Chatham, at about 7.30pm yesterday.

Just over an hour later, at about 8.45pm, the second robbery was reported at GK Cash and Carry in Canterbury Street, Gillingham.

At the Co-op, two men entered the shop with one demanding money from the cashier, who pressed a panic alarm.

The offenders left empty-handed and are believed to have run off in the direction of Hilda Avenue - after pushing a shop security guard clear of the door to get away.

"We are linking the two robberies and would urge members of the public... to contact us as soon as possible..." - DI Geoff Payne

Both men were described as white, while one was wearing a blue and grey padded jacket, black jogging bottoms with white stripes down the side, a baseball cap and black gloves.

The second man was wearing a blue body warmer with a black long-sleeved top underneath, jogging bottoms, white trainers and a black scarf over his face with stripy black fingerless gloves.

At GK Cash and Carry, a man entered the store carrying a knife and demanded money from a shop assistant.

When he ran to the till and began attempting to open it, the shop assistant left the store and locked the door, trapping the raider.

The offender then began smashing the door with his knife before running off in the direction of Mill Road.

He is described as a white man, about 5ft 8ins, wearing a black balaclava, black coat and black trousers with a hooded top.

DI Geoff Payne, of Kent Police, said: "At this stage we are linking the two robberies and would urge members of the public who might have any information, or might recognise the two people in the CCTV images to contact us as soon as possible."

Anyone with information is asked to phone DS Michelle Burgess on 01634 792332, quoting reference XY/1580/14, or Kent Crimestoppers, anonymously, on 0800 555 111.