British Prime Minister Liz Truss said she was a "fighter not a quitter" as she tried to reassert authority over the fraught ranks of her Conservative Party on Wednesday, amid growing media reports that momentum was building to oust her.

Truss is trying to shore up support from within the party after she was forced to scrap a vast tax-cutting plan, leading some Conservative lawmakers to call for her to be replaced as leader just weeks after she took office.

She has admitted her radical economic plans went "too far and too fast" after investors dumped the pound and government bonds.

However, with mortgage rates soaring and official figures showing inflation back to a 40-year high, Truss - elected by Conservative members on a promise of tax cuts and maintaining public spending - faces a struggle to convince the public and her party she could address the cost of living crisis.

Opinion polls indicate Conservatives are some 30 points behind the main opposition Labour Party, and her own ratings are calamitous.

"I have been very clear that I am sorry, and I have made mistakes," Truss told jeering opposition lawmakers as she answered questions in parliament. "I am somebody who's prepared to front up. I'm prepared to take the tough decisions."

Speculation about the prime minister's future continues to grow, with media reporting that rebellious Conservatives are weighing up who should replace her, not if she should go.

As she was quizzed on her economic policy U-turns, Conservative lawmakers in parliament looked noticeably uneasy.

"I think her position is becoming increasingly untenable," Conservative lawmaker Steve Double earlier told Times radio.

"We've seen a complete reversal of just about everything she stood for in her leadership election campaign. I think many of us are asking exactly what does Liz Truss now believe and stand for?"

Truss also faced ridicule from Labour leader Keir Starmer, who commented a new book was being written about her time in office which was due to be out by Christmas.

"Is that the release date or the title?" he asked. He later said she was asking him questions about Labour policy because "we're a government in waiting". (Reuters)