The first suspect is described as white, aged in his 20s, 5' 8", of athletic build and was wearing a khaki coloured anorak, grey or blue jeans and white sports shoes. He had a grey woollen scarf over the lower half of his face and a distinctive blue hood over his head.
The second suspect is white 5' 8" to 5' 10", of average build with black hair and wearing similar clothes to the first suspect. Call 101 or email firstname.lastname@example.org quoting Operation Garner or alternatively ring the independent charity Crimestoppers on 0800 555111.
The photos show the suspects threatening the staff. We are keen to hear from anyone who may have seen these men in the area or have any information to assist the investigation.
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Russia has announced that it will expel 23 UK diplomats in a deepening rift over the poisoning of a Russian ex-spy and his daughter.
Scores of flights were cancelled and drivers were warned to take care as the "mini beast from the east" swept in.
Sergei Skripal, the ex-Russian spy who was the target of the attack, and his daughter Yulia, remain in a critical but stable condition.