10p revolt? What 10p revolt? Scowling Brown's outburst at 35,000ft

In a fractious confrontation with senior TV journalists on his plane, the Prime Minister rejected claims that five million low-paid workers would have to pay more tax and declared: "No one will lose out."

He dismissed claims that up to 70 Labour MPs are set to rebel over the issue, saying: "It is just one or two MPs asking questions."

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And the PM faced a further blow today, after a poll showed the Conservatives are stretching their lead.

The Tories have a 10-point lead, up one point to 40 per cent, with Labour slipping three points to 30 per cent and the Lib Dems up two points on 19 per cent, according to a Sunday Mirror survey.

The research by Populus will cause particular concern in Downing Street because it suggests David Cameron's team are more trusted to guide Britain through the credit crunch fallout, by 31 per cent to 29 per cent.

The survey was carried out on Wednesday and Thursday, while Mr Brown was in the US and senior Labour figures were openly sniping at his leadership and the decision to scrap the 10p income tax band.

If the results were repeated at a general election they would give the Tories a narrow overall majority of 25 seats.

Mr Brown's frustration surfaced when challenged over the issue by reporters accompanying him on his visit to America.

The outburst drew comparisons by some with Tory Prime Minister John Major's rows with journalists on foreign trips when his authority crumbled.

Margaret Thatcher and Tony Blair kept their contact with the Press on foreign trips to a minimum – and did not reveal their disdain for them quite so openly.

Mr Brown has enjoyed generally cordial relations with newsmen since becoming Prime Minister. But he was described by witnesses as "tetchy" when he briefed them on Friday as he flew from Washington to Boston.

Notebooks and tape recorders were banned at the off-the-record briefing but The Mail on Sunday, which was not present, has obtained an account of what happened from witnesses.

The Prime Minister became irritated when the journalists kept pressing him over the 10p tax dispute.

Asked to justify increasing taxes on the low-paid, he said: "You're wrong. No one will lose out. Come on . . . you guys have exaggerated it all."

When BBC political editor Nick Robinson insisted there was a sizeable Labour revolt, Mr Brown fired back: "No it isn't. There are just one or two MPs asking questions."

When a journalist from a Labour-supporting paper insisted that the rebellion was far bigger, Mr Brown scowled: "Really? Really? That's what you say."

He was equally abrupt with ITN political editor Tom Bradby, who had asked him at the White House about the resignation threat by ministerial aide Angela Smith.

Mr Brown was forced to break off from his White House talks to beg Ms Smith not to resign. "You said a Minister was going to resign, but she didn't," Mr Brown told Mr Bradby.

Asked "What did Angela Smith say to you?" Mr Brown replied: "She just phoned me to say she wasn't resigning."

BBC Newsnight political editor Michael Crick asked sarcastically: "She phoned you up at the White House to tell you she wasn't resigning? Do all your Ministers do that?"

Another journalist put Mr Brown on the spot: "Do you acknowledge that there will be some losers from this tax change?"

The Prime Minister replied: "No. It's not as simple as that."

He then appeared to contradict his earlier statement that there would be no losers, saying: "It's impossible to say."

Downing Street advisers later summoned the reporters for two more private briefings by the Prime Minister in a move seen by some as an attempt to smooth over the row.

One adviser said: "It is ridiculous to say there was a row. He laughed at some of their remarks."