Ed Miliband ruled out a post-election coalition or deal with the SNP saying if that's what it took then there would be no Labour government.

The Labour leader went further on ruling out a pact with the Scottish Nationalists than he has gone before as both he and David Cameron attempted to persuade voters to help them win a majority in a week's time.

In a bruising 90-minute BBC Question Time both leaders said they did not want to compromise and didn't see why they would have to, despite polls indicating neither would win a majority.

Mr Miliband said: "Let me be plain - we are not going to do a deal with the SNP.

"We're not going to have a deal. If it meant that we weren't going to be in government not doing a coalition, not doing a deal, then so be it."

And he added: "I'm not going to sacrifice the future of our country, the unity of our country, I'm not going to give in to SNP demands around Trident, around the deficit or anything like that.

"I'm not going to have Labour government if it means deals or coalitions with the SNP.

"And I want to say this to voters in Scotland, there is no easy route here to vote SNP and get a Labour government."

He said he did not want to be in a coalition where each side "bartered away" their manifesto promises as the Conservatives and Lib Dems had done and added if he was prime minister he wanted to implement all of his party's manifesto.

Mr Cameron said if the Conservatives had to team up with another party to stay in power he could be trusted to "do the right thing for the country" as he did in 2010.

However, he said this time he was confident he could win the 23 seats he said he would need to win a majority.

But he added: "I believe I did the right thing in forming a coalition and having a decisive government to deal with the mess that we are left but this time, I think we can go one better."

And he said: "We can have a really decisive government, a more accountable government for you."

He also repeated his commitment to a referendum on Britain's membership of the EU - a sticking point for the Liberal Democrats.

Nick Clegg said either Mr Cameron or Mr Miliband would be prime minister but that the voters would have to decide if it was his party, the SNP or UKIP that would be a part of a deal to put them there.

However, he repeated his party's pledge for a referendum on Britain's EU membership only if there were new powers for Brussels. He said the UK should not leave the EU and said: "I cannot envision circumstances where I think it is sensible for the United Kingdom to leave the world's largest borderless market with over 500 million shoppers who buy our cause."

Mr Clegg has been setting out his "red lines" for any coalition including raising the income tax personal allowance to £12,500 and education spending.

He said that the party who got the "biggest mandate" from voters would be the party that should get the chance to try to put together a government.

However, polls have indicated his party may not win enough seats to push either the Conservatives or Labour to a majority government.

Mr Clegg said he would not quit as Lib Dem leader if the party failed to get into coalition with whoever ended up in number 10.

All three of the main party leaders were questioned on their trustworthiness during their 30-minute slots in front of the studio audience.

Mr Cameron was asked why the Tories were not trusted with the NHS, Mr Miliband was asked how Labour could be trusted not to overspend and borrow too much and Mr Clegg was asked how he could be trusted after his about-turn on student tuition fees.

Taking the first slot, the Prime Minister attempted to convince voters on welfare cuts, immigration and the NHS.

He insisted the NHS was his "life's work". And he rejected the Liberal Democrat claims the Tories were planning to cut child tax credits and child benefits if they returned to power.

But he did vow to press ahead with £13bn of welfare cuts telling the audience: "We have to reform welfare, making sure that work always pays, keeping taxes down, that is the programme. If you want unlimited welfare increases, that is Ed Miliband's programme."

Mr Miliband was given a rough ride over Labour's record in power, starting with the note left by the Chief Secretary to the Treasury Liam Byrne in 2010 which said there was no money left.

He was accused of lying when he said that the party had not overspent in power.

Mr Miliband said: "We have a global financial crisis, causing the deficit to rise, President Obama is not dealing with a high deficit because we have got schools and hospitals, he was dealing with that because of the global financial crisis."

Mr Clegg was also asked if he thought he would be asked to join any coalition after Chief Secretary to the Treasury Danny Alexander disclosed details of plans being considered by the Tories in government to cut child benefit and tax credits.

The audience was made up of 25% Conservative supporters, 25% Labour, 25 Liberal Democrat, 15% other parties and 10% who are undecided.