The "Benson & Hedges" gang struck again last night carrying out two terrifying raids on off-licences.

The attacks bring the raiders' known tally of robberies to nine in the past two weeks, stretching across the length of Brighton and Hove.

Police believe the duo, nick-named because they snatch packets of the cigarettes after stealing cash, could be responsible for at least three others.

They have launched a major operation, code-named Benson, to catch them before they strike again.

In the earlier of last night's attacks, the raiders turned to violence for the first time.

Shop assistant Nigel Hill, 42, refused to hand over cash and was floored with a headbutt after the pair burst into Threshers in Longridge Avenue, Saltdean at 8pm.

The raiders left him unconscious with a one-inch cut above his nose.

John Disano, store manager, said: "This was very frightening.

"These men need catching before something really serious happens."

Mr Disano, 55, said shopkeepers had been warned to be on guard and many were feeling edgy: "It makes you think whether it is worth doing this job."

The robbers, armed with a wheelbrace, escaped with cash from the till before driving to another target.

They arrived in Seaford just before 9pm and tried to hold-up an assistant at Unwins in Sutton Park Road.

Matthew Wicks, 24, dodged a headbutt as he pushed the offender out of the door and locked it. The accomplice was waiting outside.

Ross Cullen, 26-year-old manager, said: "It was all over in 15 seconds.

"Matthew tried to hang on to the weapon for evidence but the bloke wrestled it free. Matthew is not one to take something like this lying down.

"I'm glad he did what he did but it's not something we recommend."

Another victim told last night how he came face-to-face with the pair on Tuesday.

Robert Ford, 36, manager of Thresher's off- licence in Western Road, Hove, said: "It was all over very quickly.

"They marched into the shop, pulled a knife on me and demanded cash from the till.

"There wasn't much money in it so they forced me to open a safe and empty it.

"One of them asked me to hand over some packets of Benson & Hedges cigarettes but the other intervened and said 'Let's go'.

"They walked calmly out of the shop and got into an Astra and drove off."

Brighton and Hove CID are working round the clock to trap the pair.

Detective Inspector Pete Laverick, heading the inquiry, said he was now linking the duo to another raid on the Co-op in High Street, Rottingdean, on April 24.

The raiders entered the store at 9.15pm and threatened two male assistants with a knife before running off with the evening's takings.

The same men returned to rob the shop again on Wednesday.

Police were called at 9.30pm after staff were threatened at knifepoint. Cash and cigarettes were stolen.

One man is 5ft 9in, the other 5ft 7in with receding hair.

The pair are armed with a knife or a screw driver.