Deputy prime minster forced to defend record on health service after being accused of 'trashing a national treasure' at PMQs

Nick Clegg survived a Labour mauling at prime minister's questions on Wednesday as he faced demands to withdraw support from the NHS bill and change economic course.

Clegg – standing in for David Cameron, who is visiting the White House, faced claims from Labour's deputy leader, Harriet Harman, that the health and social care bill would lead to "fragmentation and privatisation" in the NHS.

He dismissed her comments, claiming that Labour had turned its back on reform, refused to commit more money to the health service and had indulged in "sweetheart deals" with private health firms while in government.

The Liberal Democrat spring conference refused to support the bill's third reading and several MPs rebelled on Monday night.

The remaining parliamentary pinch point for the bill will come in the Lords next week, when Lord Owen will press for it to be delayed until the government publishes the NHS risk register in line with the ruling from the industrial tribunal.

Clegg's spokesman has declined to say how the government will respond to this ruling until it has seen the judge's reasoning.

In fiery Commons exchanges, Harman said Clegg "obviously thinks he is doing a stunning job" on the NHS. She asked: "Can you explain why you have failed to persuade the doctors, the nurses, the midwives, the paediatricians, the physicians, the physiotherapists and the patients?"

Clegg told her: "The Labour party used to believe in reform. Now they believe in starving the NHS of cash."

As noise levels grew, Clegg continued his attack on Labour, saying the party's election manifesto had promised "sustained reform". He asked: "The Labour party was right then and is wrong now. What happened?"

Harman said she was proud of Labour's record on the NHS, adding that no one believed Clegg. "No wonder you can't convince those who work in the health service – you can't even convince your own conference," she added.

"People are still against this bill, because it hasn't changed one bit. It's still a top-down reorganisation, it's still going to cost the NHS a fortune and it's still going to lead to fragmentation and privatisation.

"It's clear the deputy prime minister is not going to stand up for the NHS. The only thing he stands up for is when the prime minister walks in the room."

Clegg said Labour had spent £250m on "sweetheart deals with the private sector, which didn't help a single NHS patient". He added that Labour had written NHS laws that were a "privatiser's charter", offering an 11% premium for private providers "to undercut the NHS". "Are you proud of that?" he asked.

Harman replied: "We will compare what our government did on the NHS with what your government is doing any day. You say the problem with this bill is that doctors and nurses just don't understand it. But the problem is that they do."

Making her call for the Lib Dems to block the legislation, she told Clegg: "Even at this late stage, it's within your power to stop this bill.

"Next Monday, the bill reaches its final stage in the House of Lords. There are 90 Lib Dem peers, and their votes will decide whether or not this bill becomes law. Will you instruct Shirley Williams and your peers to vote to stop the bill?"

Clegg sidestepped the question, saying the shadow health secretary, Andy Burnham, had claimed it would be "irresponsible" to increase NHS spending. "They don't believe in more money for the NHS – we do," he added.

Harman replied: "In undermining the NHS and making Shirley Williams vote for it, he has trashed not one but two national treasures.

She told Clegg: "You didn't need to sign the bill, but you did. You could stop the bill, but you won't. You say the Lib Dems make a difference, but they don't.

"What has happened to that fine Liberal tradition? They must be turning in their graves. The party of William Gladstone, the party of David Lloyd George … now the party of Nick Clegg."

Harman sought to highlight the differences over tax policy between Clegg and the business secretary, Vince Cable, saying: "These days, no one agrees with Nick. But does Nick agree with Vince?"

Clegg replied: "In government, the Labour party ran out of money; in opposition, they are running out of ideas." He said the latest rise in unemployment was "disappointing" but the problem had preceded the coalition.

"Any increase in unemployment is disappointing. It is a personal tragedy for anyone who loses their job, for them and for their families," he said.

But Clegg told Harman she "should be careful not to pretend this is somehow a problem which was invented by this government". "The unemployment of women went up by 24% under Labour, youth unemployment went up by 40% under Labour, remorselessly since 2004," he added. "So I suggest that we all need to work together to bring unemployment down."

He accused previous Labour governments of "creating the most unholy mess in 2008, which we're now having to clear up".

Earlier in the session, Clegg came under pressure from Tory backbenchers to explain why he was fascinated by Lords reform. He said he believed the Conservatives were equally interested in constituency boundary reform, and it was possible to do more than one thing at once.