As the nation draws up its New Year's resolutions the Conservatives have attacked Labour's "broken promises".

In rowdy Commons exchanges ahead of the Christmas break the Tory leader went on the offensive.

Seizing on government target slippage in the key policy areas of transport, pensions, and education, Iain Duncan Smith used prime minister's questions to put the government's record on trial.

In a week where transport policy appeared to go off the rails, he took Tony Blair to task on a 1997 to cut road congestion.

"The government has promised to cut road congestion by six per cent, has he kept that promise?," asked Duncan Smith.

Side-stepping the question the prime minister gave a brief retort: "Actually road usage is up by over 20 per cent."

The combative Tory chief was unimpressed.

"The prime minister didn't answer the question he has broken his promise," he said to Conservative cheers.

"On all figures congestion now is worse. Motorway congestion has doubled in the last four years. They've even abandoned their targets. So he has broken his promise."

Breaking from his recent practice of focusing on the detail of one issue, Duncan Smith brought pension big guns into concert with transport in a salvo on Blair's record.

"So what about the promise in 1997 to support and strengthen occupational pensions, has he kept that promise?"

An uncomfortable Blair had to fight on two fronts at the despatch box, fielding charges on a difficult terrain - scenes of the week's earlier ministerial retreats.

"I think the measures announced in the green paper on pensions yesterday will indeed help occupational pensions, and I also believe the introduction of stakeholder pensions - which are low cost private pensions for people - will also improve the situation," he told MPs.

Turning back to transport, Blair mounted the last ditch defence that gridlocked roads were actually the product of the government's economic success.

"But I may just point out on transport, that of course it is true that road usage is up by over 20 per cent, it is also true that rail usage is up over 20 per cent, indeed so is tube usage too, and that is part because the economy is immensely stronger."

The answer, insisted Duncan Smith, "is that he has broken his promise on that as well".

"Occupational pensions are a disaster.

"So what about his promise to cut school truancy by a third, has he kept that promise?," said the Conservative leader as backbench colleagues chanted, "No, no".

After call to order from the speaker, Blair returned to pensions, listing to Labour cheers a litany of government achievements.

"He says we have broken the promise on pensions. Let me tell him what we've done."

"We've introduced the £200 winter allowance, we've introduced a larger than inflation rise into the basic pension, we're introducing the pension credit form next October, we've restored free eye tests and unlike his party we've cut VAT on fuel not put it up," he told exultant Labour MPs.

"Whether its transport, or its pensions or its schools, we in favour of putting the investment in and he is in favour of taking it out."

Making an uncharacteristic humorous reference to Downing Street's difficulties with "Cheriegate", Duncan Smith compared the prime minister's defence to Cherie Blair's explanation that confusion over a flat purchase had arisen because she was too busy "juggling" her roles as PM's consort, lawyer and mother.

"Isn't it the case that when the prime minister makes promises on schools, transport, pensions, or for that matter crime, asylum, drugs or health, he's not juggling balls he is talking them?," he said.