It was hailed as the future for wine, a modern capping method which would help preserve a safer, cheaper, and more reliable vintage.

But it is claimed over two million bottles of wine sold every year in the UK which use screw tops instead of traditional corks could end up smelling of rotten eggs or burnt rubber.

More than one in 50 of the screwcap bottles could be affected by the problem, caused by a chemical process called sulphidisation, experts said yesterday.

A recent test of 9000 bottles of screwcap wine revealed 2.2% had sulphidisation and other problems connected with the contents not being able to "breathe".

The effects leave a smell of sulphur, likened by some to burning rubber, rotten eggs or burnt matches. Around 100 million screwcap bottles of wine a year are sold in the UK and the figure is rising as it becomes a popular alternative to cork.

One of the reasons for the metal caps being used was the high proportion of wine going off in bottles stopped with corks because of a chemical process known as TCA.

It is estimated that 4% of corked bottles suffer TCA, yet the problem may not be as bad as the figure suggests because when it happens to cheap wine it is not noticed.

Only a minuscule proportion of wine is ever returned to supermarket because of TCA, but if a bottle is opened to reveal the odour of sulphur, it is more likely to be sent back in future.

Plastic corks are another option, but are not believed to last as long as real cork, so can only be used for wine which has to be drunk while young, ruling out a lot of the market.

The annual International Wine Challenge (IWC) event, a prestigious gathering of worldwide tasters and critics, tests tens of thousands of wines from all over the world, including around 9000 with screwcaps and many more with corks.

It found 2.2% of screwcap closed bottles suffered sulphide or similar problems compared to 4.4% of TCA-affected cork closed bottles. Joe Fattorini, The Herald's wine expert, said: "The problem is more common among new producers who are using too much sulphur and use seals that are too tight. But the industry is working hard to correct the problem.

"Consumers very rarely return wine to stores, but if people notice this rubbery smell, they should look for an exchange or refund."