Ministers should repay £425 million borrowed from lottery funds to develop the Olympic Park by 2022, Labour has said.
Shadow culture minister Steve Reed warned charities need the cash now to help house the homeless and feed the hungry.
He added it will take 30 years for the Government to return the cash at the current repayment rate.
The previous Labour government diverted money from the Big Lottery Fund in 2007 to subsidise infrastructure for the 2012 Games, such as the Olympic swimming pool, with a promise it would be returned.
The Government earlier this year said that repayments will not start until the "early 2020s".
Speaking in the Commons, Mr Reed said: "The Government has promised to repay the remaining £425 million borrowed from the National Lottery to build the Olympic stadium.
"But at the current rate of repayment they won't pay it back for 30 years.
"Charities are struggling to house the homeless and feed the hungry this Christmas and they need that money now.
"So will the minister spread a little more Christmas cheer, back the Big Lottery Refund campaign and commit to repay the money they owe during this Parliament?"
Sports minister Tracey Crouch replied: "We are committed to repaying the funds that you refer to.
"But I can say we're working very hard to ensure that our charities across all sectors are well-funded."
She added a civil society strategy will be launched in the new year.