Before Christmas a Camra survey found that Sainsbury's was selling Carling for 54p a pint (£9.99 for 24x44cl cans), while bottled water cost 49p a pint. Without tax, the beer cost just 16p. Camra also found that Morrisons sold Grolsch for 76p a pint (£16 for 40x30cl) and Tesco sold Budweiser at 95p a pint (£9.98 for 20x30cl).
The group has tabled an early day motion calling on the government to urge supermarkets to stop cheap drinks promotions. So far 41 MPs have signed .
Camra chief executive Mike Benner said: "The ridiculous practice of the major supermarkets selling below cost for alcohol to out-price each other is reckless, irresponsible and dangerous.
"Pubs often come under unjustified attack for encouraging binge drinking, yet the industry has committed itself to curbing irresponsible drinking and cheap alcohol promotions in recent years.
"This hard work is undermined by supermarkets selling enormous quantities of alcohol at prices that simply cannot be justified."
He added: "An 18-year-old is free to take advantage of these ludicrous beer prices, walk out the supermarket door and then drink in a completely unsupervised and unsafe environment. Beer can be given by them to under-age drinkers who do not know their limits but pour premium-strength lager down their throats all night.
"This is in stark contrast to adults enjoying a drink in a pub which is regulated by law as to who it can and cannot serve.
"Something has to be done now to make supermarkets realise the damage these promotions can cause."
ACNielsen's Christmas figures show that the off-trade beer market was down 1 per cent by volume and value in the four weeks to Dec 23.