Media playback is unsupported on your device Media caption Labour leader Ed Miliband: "Every measure will be paid for either by a tax change or a change in spending"

Labour leader Ed Miliband has said Conservative claims of £20.7bn in unfunded spending pledges by his party are "completely false".

Chancellor George Osborne and other Tory cabinet ministers have said Labour's spending plans do not add up.

But Mr Miliband said Labour were being most "cautious" of the main parties.

He was speaking before a rally where he told supporters to hold four million conversations with voters before the general election.

With Labour focusing its campaign on the NHS, BBC political editor Nick Robinson said the two largest parties were attacking each other along "familiar" lines.

'Clear commitment'

Speaking on BBC Breakfast, Mr Miliband promised a "positive campaign".

"We are putting forward a positive case for a change in direction," he said.

And Mr Miliband defended Labour's economic plans, saying he had made a "clear commitment" that outside protected departments - which include health - public spending would fall.

"I'm afraid this is what the Tories are going to, the kind of campaign they're going to run," he said.

"It's going to be a choice of hope with us and falsehood from the Conservatives. The Institute for Fiscal Studies, respected independent body, has said that Labour has been the most cautious of all the parties in making commitments."

Analysis by Nick Robinson, political editor

The claims are all too familiar. You can't trust Labour not to spend and tax and borrow say the Conservatives. You can't trust the Tories with the NHS say Labour.

The facts and the claims and the spin that underpin them are new, though, and they matter.

What's also different from previous elections is the state of the public finances. Britain still has a massive deficit and growing debts so it is right that all parties should be heavily scrutinised to check they're being honest with voters about what spending they might cut, or what taxes they might increase if they get into power after May.

Read more from Nick

Addressing Labour activists in Salford, Mr Miliband said no proposals in the Labour election manifesto would be funded by "additional borrowing".

He predicted "the usual sound and fury" during the election campaign, saying the government were "pessimists".

Meanwhile, in central London, Chancellor George Osborne and Leader of the House of Commons William Hague were among the cabinet members saying Labour's plans would amount to almost £1,200 extra borrowing for every working household in the UK.

Media playback is unsupported on your device Media caption Chancellor George Osborne and other senior Conservatives said Labour's spending plans do not add up

The ministers published what they called a "cost analysis" of Labour policy, based on comments by shadow ministers. They claim Labour frontbenchers have made £23.26bn of spending proposals for 2015-16, but only £2.52bn of proposals to raise revenue in that year.

They said voters faced a choice between the economic "competence" of the Conservative party, or the "chaos" of Labour.

Labour said the document included things that would not be in its election manifesto. But Mr Osborne said it was based on "perfectly reasonable assumptions".

The figures were costed by Treasury officials under the established Opposition costing procedure, he said.

He added: "These are spending commitments made by the Labour Party since they said they were exercising iron discipline."

Time to talk

Image copyright PA

Ed Miliband says he wants his supporters to hold four million conversations with voters before polling day on 7 May

There are 122 days to go until polling day

This leaves Labour with the target of holding 32,787 conversations with voters every day

Paul Johnson, director of the Institute for Fiscal Studies, told BBC Radio 4's The World at One the Conservatives' dossier contained "things that have been said by Labour spokespeople which suggest they do not like some of the cuts".

He said: "The question is whether that would really happen if a Labour government was to be elected."

Shadow chancellor Ed Balls said the document was "riddled with errors" and renewed his call for the independent Office for Budget Responsibility to analyse other parties' spending proposals.

While the Conservatives have focused their attacks on the economy, Labour chose the NHS for its first campaign adverts.

Shadow health secretary Andy Burnham told BBC Radio 4's Today programme the health service would change "beyond recognition" if the Conservatives won power.

Media playback is unsupported on your device Media caption Nick Clegg compared Labour to an unreliable ex-partner and the Tories to a dodgy mobile phone salesman

Meanwhile, on a busy first Monday back at Westminster after the festive break, Lib Dem leader Nick Clegg called for "a strong coalition government, with Lib Dems anchoring it in the centre ground".

Voting for his party was the only way to support "the national interest against petty populism", the deputy prime minister said at a press conference.

Mr Clegg said Conservative plans to tackle the deficit were "a con", while Labour's policies represented a "clear and present danger" to the economic recovery.