The Government has broken its promise to introduce new laws forcing pubs to serve a 100 per cent liquid pint, according to consumer group the Campaign for Real Ale (CAMRA).
CAMRA claims ministers have broken a pledge made in their 1997 election campaign to bring in the new legislation during their first term in office.
Research by the consumer group earlier this month found that many pints served were short by more than five per cent and some by as much as 10 per cent, which the group claims is short changing consumers by up to 20 pence a pint.
Mike Benner, head of campaigns at CAMRA, said the Government had promised to bring in new laws to guarantee drinkers a 100 per cent liquid pint.
"The Government has made a clear commitment to full pints to deal with the growing problem of customers being ripped off in some pubs, but the issue is being bounced around like a yoyo in the corridors of power," he said.
"It's quite simple. A pint of beer should be 100 per cent liquid and no pub should be able to profiteer from the current system of self-regulation which has clearly failed."
But a more efficient system of self-regulation could help the trade fight back against CAMRA's concerns.
Linburn Technology, a Dunfermline-based company which manufactures equipment for the pub trade, is trialing a new system called Head Miser, which calculates the exact percentage of liquid in a pint and can store the figures on a central database.
Linburn's managing director Jim Mitchinson said the results of the trial can be used to support the industry's argument for self regulation.
"If we start gathering data and start being more open with the regulatory bodies such as trading standards then maybe there's a chance of self regulation working," he said.
But CAMRA claims its research discovered the average beer measure in town centre themed pubs was less than 94.7 per cent, with one beer containing 87 per cent. CAMRA ordered 17 pints of different beer brands in six national branded pubs in Cardiff. The measures were taken after the head on the beer was dissolved leaving only liquid. Ten of the 17 beers contained less than 95 per cent liquid.
Mr Benner said: "There is clear need to protect consumers. We urge the Government to stick to its commitment and introduce full pints as soon as possible.
"Drinkers should not have to ask for a top up. They should consistently get a full pint first time."
The Government said it was committed to introducing full pints but suffered embarrassment when its Small Business Service, which was investigating the need for legislation, claimed it was unnecessary. However a spokesman for the Labour party confirmed: "If it is re-elected, the Government will be revisiting the issue of pint measures shortly after the General Election."