David Cameron was accused of double standards after calling for fathers who abandon their families to be "stigmatised", while backing policies which could make it more costly for mothers to pursue them for financial support.
In an article yesterday, the Prime Minister said "runaway dads" should feel the "full force of shame" in a similar way to drink drivers.
Labour said government reforms would make it easier for fathers to escape their financial responsibilities, by charging mothers to use the Child Support Agency. Earlier this year, the Government announced a consultation on proposals to encourage parents to reach their own arrangements for child maintenance – rather than relying on the state – by introducing a fee.
Writing in The Sunday Telegraph to mark Father's Day, Mr Cameron said it "simply isn't acceptable" for single mothers to be left to bring up their children on their own. Even when parents were separated, he said, fathers had a duty to support "financially and emotionally" their children.
Where men were unwilling to face up to family obligations, Mr Cameron said society should make clear such behaviour was unacceptable.
"It is high time runaway dads were stigmatised and the full force of shame was heaped upon them," he said. "They should be looked at like drink drivers, people who are beyond the pale. They need the message rammed home to them ... leaving single mothers, who do a heroic job against all odds, to fend for themselves simply isn't acceptable."
Mr Cameron also indicated his determination to introduce tax breaks for married couples – an election pledge which appeared to have been dropped in the face of opposition from the Liberal Democrats and scepticism from the Chancellor, George Osborne.
"I want us to recognise marriage in the tax system so as a country we show we value commitment," he wrote. He described how he learnt his values from his own father, Ian Cameron, who died last year aged 77.
"From my father, I learned about responsibility. Seeing him get up before the crack of dawn to go and do a hard day's work and not come back until late at night had a profound impact on me," he said.
The shadow Chancellor Ed Balls said Mr Cameron's approach was deeply flawed."Fathers should take their responsibilities seriously, but he is charging mums when the father leaves now to go into the CSA [Child Support Agency]," Mr Balls told the BBCs' The Andrew Marr Show. "He is going to make it harder with his marriage tax cut [which] will disadvantage the woman left behind and give the tax break to the father who goes off."