The election campaign formally started after Parliament was dissolved.

- The Conservatives defended a claim that working families faced a £3,028 average tax rise under Labour after a leading think tank said the figure was "unhelpful"

- Ed Miliband launched Labour's business manifesto amid a row over corporate backing for its EU policy

- Nick Clegg said the Lib Dems would occupy the "reasoned centre ground" during the campaign

- UKIP leader Nigel Farage unveiled his party's five main election pledges

- The Green Party of England and Wales said it could be in a "decisive" position if there's a hung parliament

- Chancellor George Osborne said details of the Conservatives' planned £12bn welfare cuts would be set out in a spending review after the general election

- Three new polls suggest a Conservative-Labour tie (Populus), a 2%Conservative lead (Ashcroft) and a 4% Conservative lead (ComRes)

We're ending our coverage for the day now - thanks for joining us. We'll be back again at 0600 on Tuesday.

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On Newsnight,Tony Blair's former director of communications Alastair Campbell said it seemed as if there was a "post-match analysis" going on, instead of an examination of policies and what the election is about. Of the main leaders, he said only Ed Miliband could "emerge in a different light".

Conservative peer Lord Finkelstein said the question for the Tories was whether they could "project their record forward" and show their vision. He added that he would not advise Labour to focus on the idea of "Ed Miliband over-performing".

Meanwhile, the former Lib Dem press secretary Miranda Green wondered where the parties would find "optimism" against a "background which is really grim". People were worn out by austerity and were hankering after something more, she said.

On Newsnight, Evan Davis quizzes Conservative Party Chairman Grant Shapps on the claim that a Labour government would mean working families would pay an extra £3,000 in tax in the next parliament.

Grant Shapps says the Conservatives stick by that calculation and would not impose more taxes themselves, but Evan Davis tells him the claim is "obviously ridiculous" and the Institute of Fiscal Studies has found it to be so.

BBC Political Correspondent James Cook reports that "last year politics came alive in Scotland".

"Scotland rejected independence but that fervour has not died down..there is a dramatic battle for Scotland's 59 seats."

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David Cowling, Editor, BBC Political Research, writes:

"Following the flurry caused by YouGov’s 4% Labour lead this Sunday, we had three polls on Monday telling a different story. Populus had Conservative and Labour tied on 34%; Ashcroft had a 2% Conservative lead (36% versus 34%) and ComRes had a 4% Conservative lead (36% versus 32%).

"Among all four polls, the average Lib Dem rating was 8%; UKIP’s was 13% and the Greens around 6%. We’ve barely started our long road to 7 May but perhaps this campaign will develop into a battle of methodologies – telephone versus internet polls.

"The two telephone polls (Ashcroft and ComRes) had the highest Conservative ratings – 36% each; and the two internet polls (YouGov and Populus) had the lowest – 34% and 32%. YouGov represented a 5.5% swing from Conservative to Labour, enough to give Labour a majority. ComRes suggested a 1.5% swing to Labour, barely a ripple on the election pond."

On the first formal day of the general election campaign -- the party leaders have begun setting out their positions:

- David Cameron said he wanted to complete the job of turning the country around and that voters faced a "stark choice" between the Conservatives and Labour

- At the launch of Labour's business manifesto, party leader Ed Miliband said the Tories' EU policy threatened business

- The Liberal Democrats said they would keep a future coalition "anchored in the centre ground"

- UKIP leader Nigel Farage unveiled his party's five main election pledges

- Welsh Labour and Welsh Conservatives launched their campaigns

- The Green Party of England and Wales said it could be in a "decisive" position if there's a hung parliament while The Green Party of Scotland launched its manifesto, including a pledge of a £10 minimum wage.

BBC Political Correspondent Vicki Young says the crucial difference between this election and the last one is that "it's a much more crowded field", with smaller parties playing a bigger role.

Tory peer Lord Ashcroft's latest weekly survey showed his party gaining three points to 36% on last week - when the two main parties were neck and neck - with Labour up one to 34%. The Liberal Democrats were down two points at 6% and UKIP dropped to 10%. The Greens were up two points to 7%, while the SNP fell two points to 4%.

Shadow justice secretary Sadiq Khan said he would not buy one of Labour's immigration mugs - because the message on them was not clear.

"I personally would not buy the mug," he told LBC radio's Iain Dale. "I think it can be misconstrued and what's important is that we are quite clear what we mean by our policies...Sometimes people misunderstand what the mug means."

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The Conservatives will not publish details of their planned welfare cuts until after the general election, Chancellor George Osborne has confirmed. Mr Osborne said they would set out how they intend to achieve the planned £12 billion in savings from the welfare budget in a summer spending review, if they are returned to power after the election. He told Channel 4 news: "We will set out our plans as part of a spending review when you can make these balanced judgments."

Jon Trickett, Labour’s shadow minister without portfolio, says the idea of UKIP working with the Conservatives in the event of a hung parliament would be a disaster. UKIP leader Nigel Farage says he has had "informal" conversations with Conservatives about working with them to secure an EU referendum in the next parliament - but not with ministers.

Mr Trickett said: "UKIP do not stand for working people because they are too busy planning to join the Tories. They are a party of Tory money, Tory people and Tory policies.

"It is growing increasingly clear that UKIP and the Tories are prepared to work together, which would be a disaster for working families' living standards and British business."