Detectives fear violent robbers may have struck city shops three times in as many days.
Police are linking a knifepoint robbery at Asda Brighton Marina with armed robberies at off-licences on the previous two nights.
A man entered the Asda store shortly after midnight on Friday and threatened the cashier with a knife. He ran off with about £1,300.
Witnesses saw him get into a white saloon car outside the supermarket.
Detectives say they are growing increasingly concerned as they are linking the Asda incident with similar robberies on Wednesday and Thursday nights.
Anyone with information should contact Sussex Police on 0845 6070999.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article