Web surfers have been plagued by a 'significant increase' in the volume of spam emails trading on the name of the luxury watch manufacturer Rolex during the last week, researchers have noted.

Global monitoring by IT security firm Sophos has recorded a 300 per cent rise in the number of junk emails referencing Rolex in the last month.

"Spammers hawking cheap watches are the internet equivalent of Del Boy and Rodney, but few computer users who have to wade through a barrage of unsolicited emails every day will find their antics amusing," said Graham Cluley, senior technology consultant at Sophos.

He added that spam continues to be a "nice little earner" for spammers because people continue to purchase goods sold via junk email.

Earlier this year, pharmaceutical giant Pfizer - the maker of Viagra - announced that it was taking legal action against dozens of illegitimate online pharmacies to block sales of counterfeit drugs and help reduce spam.

"It's not the first time that a big brand has been targeted, and it's unlikely to be the last, but it will be interesting to see what action Rolex takes to protect its name from the abuse of spammers," said Cluley.