David Cameron has told MPs he will "deal with" cheap alcohol being sold in supermarkets in England and Wales.
It comes after reports the government has ditched plans for 45p per unit minimum alcohol pricing.
Tory MP Sarah Wollaston called on the PM to stick to the plan, saying it would cut crime and early deaths.
Mr Cameron said the government was considering the outcome of a consultation but said sales of "20p cans of lager" had "got to change".
"There is a problem with deeply discounted alcohol in supermarkets and other stores and I am absolutely determined that we will deal with this," he told MPs.
Earlier, Labour leader Ed Miliband, who backs minimum alcohol pricing, attacked Mr Cameron over his "U-turn", asking MPs: "Is there anything he could organise in a brewery?"
The Labour leader's jibe reduced MPs, including Mr Cameron, to laughter at Prime Minister's Questions.
Mr Cameron said he would like to hold a party in a brewery in his constituency to celebrate the continued presence of Ed Balls as shadow chancellor in Mr Miliband's top team.
Mr Milband replied: "He obviously couldn't tell us about his policy on alcohol, minimum unit pricing, Mr Speaker. I think the reality is he has just been over-ruled by the home secretary on this one."
The PM has long supported minimum alcohol pricing but is reported to have clashed with cabinet colleagues, including Home Secretary Theresa May, whose department is responsible for the policy, Education Secretary Michael Gove and Commons leader Andrew Lansley on the issue.
Mrs May, who has been touted by some as positioning herself as a possible future Tory leader, took up a low key position in the Commons chamber - away from the front bench - during PM's questions.
Lib Dem business secretary Vince Cable appeared to confirm the policy has been dropped in an interview with BBC Radio 4's You and Yours, saying it was a "good concept" he "would have liked" to have seen become law.
Mr Cable said his party was in a coalition and there would have to be compromises.
Reports that minimum pricing has been dropped have angered health campaigners and some Conservative MPs concerned about the health impact of drinking, although others have welcomed the news because they say it will avoid responsible drinkers being unfairly penalised.
BBC political editor Nick Robinson said that while there had been no official confirmation the plans would be dropped, sources involved in the discussion said the policy was "in its death throes".
He said the chancellor was expected to set out the government's approach to alcohol pricing in next week's Budget.
Conservative MP Tracey Crouch, who backs the plan for a minimum alcohol price, told the BBC the rumoured shift was "more about politics than policy".
"I'm very disappointed to see that Theresa (May) has changed her mind on this policy," she said.
"This is about political manoeuvrings perhaps rather than actually looking at the long-term health of the nation."
The Home Office said it was considering all representations to its consultation on the measure and would report back in due course.
If a 45p unit price were to be introduced, a can of strong lager could not be sold for less than £1.56 or a bottle of wine for less than £4.22.
The department is also considering banning multi-buy promotions, such as two-for-the-price-of-one.
Tory MP and ex-GP Sarah Wollaston told BBC Radio 4's Today programme that she was "devastated" at reports minimum pricing would be dropped, describing problem drinking as "an absolute health crisis".
"We know that whenever alcohol is too cheap, people die," she said. "If the chancellor wants a message from me, it's that we're already paying a huge amount to clear up the cost of this - around £21bn a year just to deal with the crime, violence and medical costs of it."
She said any rise in alcohol duty would not tackle the problem of supermarkets discounting alcohol at very cheap prices, around 22p a unit, which was "causing carnage".
But fellow Conservative, former shadow home secretary David Davis described minimum pricing as a "blunderbuss policy" which would punish responsible drinkers on low incomes and pensioners.
He said there was no evidence minimum pricing worked because "alcoholics are not sensitive about the pennies". He called for more to be done to stop shops selling alcohol to under-age drinkers and make pubs deal with drunk people on their premises.
Dr Vivienne Nathanson, director of professional activities at the British Medical Association, said she was surprised to hear rumours of the climbdown as she believed Mr Cameron was "quite clearly in favour of it".
She added: "[Mr Cameron must] be courageous. This is a once in lifetime opportunity to save lives and save the country money."
But the Wine and Spirit Trade Association said recent figures showed alcohol consumption was falling and there was little evidence showing that a minimum price would reduce problem drinking.
"Minimum unit pricing would penalise responsible drinkers and treat everyone who is looking for value in their shopping as a binge-drinker," said the body's chief executive Miles Beale.
Devolution has meant different strategies have been developing to tackle rising rates of problem drinking across the UK.
In addition to the 45p consultation in England and Wales, in Scotland a 50p price is set to be introduced.
Northern Ireland is yet to put forward a specific proposal, although it is reviewing pricing.