The Conservatives have been accused by Labour of favouring the rich after the Chancellor refused to rule out cutting the top rate of income tax in a Sky News interview.

George Osborne, who has repeatedly refused to rule out a tax cut for high earners if the Tories win on 7 May, told the Murnaghan programme his party had "no plans" to further reduce the top rate of tax and insisted it was not a priority.

Prime Minister David Cameron also said: "It's not our policy, it's not our plan."

But Labour claim the Chancellor has been "flushed out", pointing out Mr Osborne used the same words about VAT before the last election, which he then raised from 17.5% to 20%.

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The opposition has promised to bring back the 50p rate for those earning upwards of £150,000, claiming the cut to 45p had benefited the wealthiest by at least £85,000.

Pressed on whether top earners could be in line for another tax cut, Mr Osborne said: "You can judge us by what we say we want to do.

"And what we want to do is increase the tax-free personal allowance to £12,500 so people full-time on the minimum wage don't have to pay income tax and millions are better off.

"And when it comes to higher rate taxpayers our priority is increasing the threshold at which you pay that higher rate, the 40p rate, to £50,000.

"Those are our big tax commitments for the coming parliament."

Tackled repeatedly over whether the top rate could be cut further, Mr Osborne said: "If that was our priority or our plan we would have made it part of our plan and made it one of our priorities."

But Labour's Chris Leslie told Murnaghan this was the same argument previously used by Mr Osborne on VAT, which he had then increased.

The party's priority, he claimed, "is always about helping the very richest in society".

Mr Leslie said later: "The Conservative Party's secret plan has now been exposed.

"Asked four times, George Osborne repeatedly refused to rule out another top-rate tax cut for millionaires.

"The Tories have raised taxes for millions but cut them for millionaires.

"And it's now clear that if they win the election they'll do the same again."

The clash over tax is just the latest between the two main parties as the election campaign gets into full swing.

In recent weeks, Mr Cameron ruled out an increase in VAT while Labour committed not to increase National Insurance.

Mr Osborne also warned "an unholy alliance" between Labour and the SNP after the election would threaten the future of the UK and its economy.

SNP leader Nicola Sturgeon has offered to help Ed Miliband "lock David Cameron out of Downing Street" as she sought to bat away disputed claims she had told the French ambassador she would prefer a Tory win.

But Mr Leslie said Labour had ruled out a coalition with the SNP.

"The SNP and the Conservatives, I think, are playing political games with the country's future," he said.