Oxfam has rejected fresh criticism from a Tory MP over a campaign attacking the Government's austerity drive.
The charity said it stood by an assertion that 20 million meals were distributed last year to people who could otherwise not afford to eat.
Bournemouth MP Conor Burns said more than half of those meals had been distributed by a charity that supplies community cafes, women's refuges and pensioner lunch clubs which are not means-tested.
Calling for a correction, he said: "While I fully support the work that charities like Oxfam do in supporting the most vulnerable in society, including in my own constituency, I think it is wrong for them to make such powerful and emotive claims that are not backed up by the evidence that they supply.
"It is vital that the debate on such an important issue is based firmly on facts, and not on fallacy."
But a spokesman for Oxfam - already the subject of a complaint to the Charity Commission by Mr Burns over what some Tory MPs attacked as an "inappropriately political" online campaign - defended the Below the Breadline report.
"We stand by our report, which was produced by three non-partisan charities with expertise in tackling UK poverty," he said.
"If Mr Burns has concerns over our figures, we hope he will support our call for the Government to collect official data on food poverty in the UK, the lack of which is hampering the fight against hunger."
The 20 million figure was included in a press release used to promote the report - which was jointly issued with the Trussell Trust and Church Action on Poverty - and was said to represent a 50% rise.
But the report itself noted that "food redistributed by FareShare contributed towards more than 12 million meals".
"As these are not all means-tested, it is simply not possible to state that these meals are consumed by people 'who could not afford to feed themselves' - an incredibly emotive and powerful claim, but sadly one which is unsupported by the evidence you have referenced," Mr Burns said in a letter to the charity.
"Government is understandably held to account for its use of statistics, so could you please explain how you can justify this claim, and what you intend to do to correct the statement?"
Several Tory MPs were outraged by a faux film poster issued by the charity on Twitter depicting a raging sea under the tag line: "The perfect storm... starring zero-hours contracts, high prices, benefits cuts, unemployment, childcare costs."