Masked raiders, one armed with a machete, threatened staff at a fast-food restaurant and grabbed cash from the safe.

One teenage assistant tried to fight them off but he was knocked to the ground.

The robbery at Uncle Sams in Carden Avenue, Patcham, Brighton, happened at 10.30pm on Sunday.

The three men, wearing balaclavas, oburst in and leapt over the counter, startling the three members of staff.

Co-owner Deborah Tunesi said: "They were swearing and shouting. My assistant tried to stop them but he was knocked to the ground.

"One of the men produced a machete and my assistant stopped struggling. Fortunately he wasn't hurt."

The raiders grabbed what police described as a "substantial" amount of cash from the safe.

The robbery was the second at the restaurant in seven months. Just before Christmas two men, both wearing balaclavas, jumped the counter and took money from the safe.

Mrs Tunesi, 34, runs the restaurant with her husband Adam, 39. They have a seven-year-old son.

Mrs Tunesi said they were considering selling up after this latest raid. She said: "It crossed our minds after the first robbery.

"You never think it will happen again. We are trusting people and we think everyone else is the same. But the world isn't like that, unfortunately."

The raiders fled down an alley into the Patcham Estate. Witnesses or anyone with information should contact Brighton CID on 0845 6070999.