Media playback is unsupported on your device Media caption Mr Cameron said he was "very happy" to be judged on his record since 2010.

Prime Minister David Cameron has defended his government's record as the parties stepped up their campaigning ahead of the general election.

Mr Cameron said Tory plans for post-election spending cuts were "moderate".

He also responded to Labour's latest attack over the NHS, saying he would commit the funds needed to shore up the service in the future.

Labour has said the NHS would be left "unrecognisable" if the Conservatives win the election.

Speaking on the BBC's Andrew Marr Show days after unveiling the Conservatives' first campaign poster for the general election, Mr Cameron said he was "very happy" to be judged on his record since 2010.

In the wide-ranging interview, he also:

Claimed Labour would spend an extra £13.5bn on debt interest because of slower spending cuts

Made a "commitment" that the regular Armed Forces would not be reduced further in the next parliament

Said maintaining the Nato target of spending 2% of national income on defence "depends on what happens on the economy"

Said he would like to see a referendum on EU membership - which is promised by 2017 - as soon as possible

Suggested Conservative ministers would not be given a free vote on leaving the EU

Criticised UKIP, saying the party had "clearly got some issues"

Labour said the Conservatives' deficit attack was based on "false assumptions and out-of-date economic forecasts", while the Lib Dems said only they offered a "fair and balanced approach".

UKIP leader Nigel Farage said the prime minister had been "incredibly rude" about his party while trying to "sound a little bit like us".

NHS attack

BBC political correspondent Chris Mason said general election campaigning was stepping up, with MPs returning to the House of Commons on Monday.

"Labour are determined to talk about the health service, the Conservatives about the economy," he added.

In a "start of the race" note to activists, Labour's election strategy chief Douglas Alexander called for a campaign to "save" the health service.

The document claims waiting time rules have been breached and says there is a "staffing crisis" in the NHS.

Image copyright PA Image caption Labour has launched a poster campaign, mimicking the Tories' 2010 adverts

Image copyright Conservative Party Image caption The Conservatives' first campaign poster focused on the economy

Labour claimed seven of out 15 patients' rights enshrined in the health service's constitution had been breached.

The party also claimed it had become harder to book a doctor's appointment.

'Great institution'

A Conservative spokesman disputed Labour's figures and said Labour leader Ed Miliband's lack of an economic plan "would put the entire NHS at risk."

Mr Cameron, who described himself as a "compassionate Conservative", said: "We've said very clearly we'll protect the NHS - it's very precious to me, it's very precious to Britain.

"It's a great institution that we should be enhancing and not undermining."

The prime minister also reiterated an attack on Labour's deficit reduction plans, saying his party's proposals for £30bn of extra cuts were "not some ideological obsession".

"It is moderate, it is sensible, it is reasonable," he said, claiming Labour's plans would lead to "real poverty".

He also dismissed Lib Dem warnings about defence cuts, saying his coalition partners were trying to sound "relevant".

And asked whether he had abandoned his bid to limit the free movement of people across Europe, he said his proposed curbs on EU welfare would help to bring down net migration to the UK.

He said his proposals would require "proper, full-on treaty change".

'Status quo'

Labour responded to the Conservatives' debt interest attack by asking Treasury officials to carry out costings for the main parties' spending plans.

Shadow chancellor Ed Balls said the £13.5bn projection was based on "false assumptions about Labour's fiscal plans".

Meanwhile, shadow business secretary Chuka Umunna responded to former Prime Minister Tony Blair's warning that a "traditional left-wing party" risked losing the election by saying Labour was "firmly anchored in the centre ground".

"I do not believe we have moved left or right", he told Sky News.

Lib Dem Justice Minister Simon Hughes said the Conservatives would cut spending "more than is acceptable" while his party offered a "balanced resolution" involving tax rises.

UKIP's Mr Farage said NHS savings could be found "without any shadow of a doubt" and described Mr Cameron and Labour leader Ed Miliband as "agents of the status quo".