Supermarkets have ruled out increasing alcohol prices and said they are not to blame for town-centre binge-drinking.
They also refused to be drawn on whether they use alcohol as a loss-leader, during a grilling session with MPs from the All-Party Parliamentary Beer Group at the House of Commons.
Group chairman John Grogan also said he is to discuss the issue of cheap supermarket alcohol with Home Office and Department of Health ministers in the next month.
Representatives of the four biggest supermarkets were called in, in response to Grogan's early day motion - which has been signed by 188 MPs - against cheap off-trade booze.
Sainsbury's head of legal affairs Nick Grant said: "As retailers, we can't and will not agree to raise prices - to do so would be unlawful and anti-competitive.
"It would be against the customer's wishes and against the idea of customer choice."
Asda head of government affairs Bernard Hughes said: "Price is in our DNA and we won't increase prices to make our customers pay more.
"Price is something that is non-negotiable for us."
Hughes rejected claims that home-drinking fuels problems in town centres.
"I would not accept that supermarkets are responsible for drinking in town centres," he said. "It's a very complex thing and it's easy for some publicans to blame the supermarkets."
On the issue of selling alcohol at a loss, Hughes said: "In my experience the question is not anything as arbitrary as loss leaders. What is meant by 'no-margin' or 'nil-margin'?
"It's complicated - it means different things to different people at different times."
Hughes said a proposal for a voluntary agreement not to sell alcohol as a loss-leaders "would be impossible to police and an accountancy nightmare".
Busting myths
Sainsbury's Nick Grant vowed to "bust myths" about the link between alcohol pricing in
supermarkets and
excessive drinking.
"Ninety per cent of
customers who bought beer in bulk from Sainsbury's said they would drink about the same as in a usual month," he said.
The supermarket
representatives argued that people who buy discounted alcohol in shops would usually "stock up", rather than drink it immediately.
They pointed to
responsible steps they had taken, such as having warning labels on drinks and point-of-sale material, and tightening up on age checks - Asda will trial "Challenge 25" in the next week, said Hughes.
They pointed out factors that led to problem drinking, such as lack of parental responsibility or clarity about alcohol units. "The debate should be about changing culture through education, not a tilted debate about price," Grant said.