David Cameron claimed Mr Brown had been caught "red handed"
Gordon Brown has defended his spending pledges after David Cameron accused him of giving MPs misleading figures.
The Conservative leader said Mr Brown told MPs last week that capital spending would rise up to 2012 when it would actually fall in coming years.
He said Mr Brown had been caught "red-handed" and should apologise.
Mr Brown said Labour had brought forward future spending to counter the recession and investment was far higher than it had been under the Tories.
At Prime Minister's Questions, Mr Cameron said Mr Brown had given inaccurate information to MPs last week about capital expenditure growth between now and 2012.
He said Mr Brown had claimed that spending would rise every year until 2012 while, in fact, it would fall from £44bn in 2009-10 to £26bn in 2012-13.
"The prime minister has been caught absolutely red-handed"," he said.
Mr Brown could not bring himself to admit that spending was falling under Labour, accusing him of not be able to give a "straight answer".
But Mr Brown said spending had been brought forward to help protect jobs and keep people in their homes in the face of the recession and to pay for Olympic projects.
Capital expenditure would be higher this year than at any time under a Conservative government, he said, while accusing the Tories of planning "savage" cuts in spending after the next general election.
However, he acknowledged that, under current plans, capital spending would fall after 2009-2010.
For the Lib Dems, Nick Clegg said Gordon Brown was "dressing up cuts as investment".
He said the PM had performed u-turns on a huge number of issues in recent weeks and would soon have to admit he was also "wrong" on public spending.
The clash was the latest in a series of angry exchanges between the two leaders over public expenditure in recent weeks with each accusing the other of concealing the levels of cuts in spending required after the next election.