Image copyright PA Image caption Mr Burnham said Labour should "build on" its last election manifesto

Andy Burnham has called for 18-20 year olds to be paid the same minimum wage as older workers as he and other Labour candidates addressed a union hustings.

He said he would scrap the lower rate for young adult workers, currently paid £1.37 less than older colleagues, as an "hour's work deserves an hour's pay".

But he rejected calls for the main rate to rise to £10 an hour by 2020.

Liz Kendall and Yvette Cooper said the Low Pay Commission should be left to decide on differential rates.

And Jeremy Corbyn said the lower rate was "very strange".

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The four candidates vying to succeed Ed Miliband have been questioned by union members at an event hosted by the Trade Union and Labour Party Liaison Organisation, one of series of hustings taking place over the summer before September's election.

The event was preceded by sniping between the rival candidates' camps with MP John Woodcock, a key ally of Ms Kendall's, claiming he had been briefed against after warning of the dangers of Labour electing a "continuity Miliband" candidate.

Ms Kendall said Labour faced a huge task getting back into power and would only do so when it regained the trust of people on the economy and was able to offer a vision of a "better life", saying these were not exclusively "Tory values".

Image copyright Reuters Image caption Liz Kendall is seeking to differentiate herself from her rivals but some supporters question her authority as leader

Analysis by BBC Political Correspondent Iain Watson

Liz Kendall had two objectives in mind in her speech this morning - further differentiating herself from her Labour rivals by putting a strong and positive emphasis on the need for fiscal responsibility and, secondly, trying to burnish her credentials as the candidate the Conservatives fear most.

As one of her supporters said, she is attempting to avoid being the opposition George Osborne would want Labour to be. So there was a straightforward admission that a lot of taxpayers money is spent - in tax credits - to subsidise low pay.

But there's a feeling, even amongst some Blairites, that Liz Kendall is still a work in progress.

One Labour-supporting audience member said: "She is saying all the right things about the scale of the defeat, but I am still not convinced she is the right person to be saying it. I admire her courage, but I am not sure she has the authority to be leader."

She didn't seize the opportunity to put more distance between herself and Ed Miliband on some issues. Nonetheless, she was calm and assured under sustained questioning and delivered her core message with confidence. She may have to show more confidence, though, in departing from her script.

But her supporters are convinced she is making the political weather and are portraying her opponents as more of the same.

"People need to think about who is the leadership candidate that isn't just going to argue for a little bit of change, who is going to face up to the scale of the challenge, who is going to be the candidate that the Tories really fear because they are facing head on people's concerns about their money, about welfare and have a properly broad pitch."

Despite the party's heavy defeat last month, Mr Burnham said Labour must "build on" the manifesto that it stood upon rather than disown it completely.

"It had more to say to my constituents than any other manifesto I had stood on," he said. "But the point is it didn't have enough to say to the whole country. So we don't rip it up, we build on it."

'Labour values'

Urging changes to minimum wage rates, the shadow health secretary said it was unfair to pay 18-20 year olds less than the full minimum wage, currently £6.50 an hour.

He said he would scrap the lower rate, currently £5.13, if he was prime minister, while keeping existing rates for under-18s and apprentices. He said he would also stick with a manifesto commitment to raise the main adult rate to £8 an hour by the end of the Parliament in the face of union calls for a higher £10 rate.

"It is hard enough for young people to get on in life, what are we making it harder? Why are we pulling the rug from under them."

Ms Cooper said the party must choose a leader who could "look like a prime minister from the start" not just an opposition leader. "We have to make sure that is about being a Labour prime minister and being proud of Labour values," she said.

And Mr Corbyn said Labour must oppose all spending and welfare cuts announced in next week's Budget.

"Austerity is a code word for greater inequality," he said. "The 100 richest people in this country own the equivalent of 30% of the wealth of the rest of the population. That is grotesque inequality and it is getting worse."

In a speech in the City of London before the hustings, Ms Kendall called for major changes to the government's programme to help the long-term unemployed find work and said the Low Pay Commission should encourage more employers to pay a living wage.

Mr Burnham, meanwhile, also announced plans for a review of charges for workers seeking to take their employers to a tribunal.