David Cameron has criticised Jeremy Corbyn for describing the so-called "national living wage" as a "corruption" of the idea.
The Labour leader insisted he supports the increase in the minimum wage to £7.20 an hour for over-25s but stressed that it was not high enough to justify the Government's description of it as a living wage.
The Prime Minister seized on the comments and told Mr Corbyn to thank the Government for giving some of Britain's poorest workers a £20 pay rise.
In a wide-ranging session of Prime Minister's Questions, Mr Corbyn and Mr Cameron clashed over EU proposals to close loopholes in rules that stop wage undercutting in countries hosting temporary foreign workers.
The Opposition leader asked Mr Cameron if the Government supported plans to strengthen the rules to ensure temporary workers posted to foreign countries do not undercut the local population.
The Prime Minster said he saw merits in the plan but did not commit to backing it.
He then urged Mr Corbyn to celebrate the "living wage" as a victory for workers' rights.
But the Labour leader hit back: "The national minimum wage was a Labour introduction, the national living wage proposed by your friend the Chancellor is frankly a corruption of the very idea of it.
"It is not in reality a proper living wage.
"But my question was about the posting of workers directive which would prevent the grotesque exploitation by unscrupulous employers of workers being moved from one nation to another in order to undercut the wages of the second nation.
"Will you be absolutely clear - will the British Government support this very, very important reform to stop this exploitation?"
Mr Cameron replied: "We are working with the Dutch presidency, we think there's merit in a lot of the proposals, but we want to make sure we get the details right.
"But let me pull you up on something - you have just described the national living wage as a corruption.
"The national living wage - £7.20 an hour, a £20 a week pay rise for some of the poorest people in our country.
"I really think you ought to get up and say you support the national living wage and thank the Government for introducing it."
Mr Corbyn replied: "I support a wage rise obviously, the point I'm making is that it is not a living wage as is generally understood."