Ed Miliband says a Labour government would set a statutory minimum wage target linked to average earnings, as he sets out plans to tackle low pay.
Labour will not announce the exact figure until nearer the general election, BBC political correspondent Vicky Young said.
But she said a party source had told her it would be a "stretching target".
Both the Conservatives and Liberal Democrats have already said they want a rise in the minimum wage.
However any major increase is likely to be criticised by business groups.
They are worried that it would drive up costs and damage competitiveness.
The Labour leader is due to unveil a report by Alan Buckle, the former deputy chairman of KPMG International, which details proposals to overhaul the Low Pay Commission.
Mr Miliband says he wants to write the next chapter in the history of Labour's battle to make work pay and he is pledging to increase the national minimum wage so it gets closer to average hourly earnings.
It is the first time the party has suggested a long-term link between the two and it wants the Low Pay Commission to be given a far broader remit including a wider duty to tackle poverty and raise productivity across the UK.
Labour will not say what the final level for the minimum wage would be but a source said it would be a "stretching target", not just what a future government could get away with one year to the next.
'Hard day's work'
In a speech following the launch of the report, Mr Milliband is expected to tell party activists in the West Midlands: "Britain is still one of the lowest paid countries among the world's advanced economies.
"So we have to go further, we have to write the next chapter in the history of Labour's battle to make work pay.
"That's why today, I am proud to announce that the next Labour government will take new radical action against low pay: a new five-year ambition to restore the link between doing a hard day's work and building a decent life for your family.
"A Labour government will establish a clear link between the level of the minimum wage and the scale of wages paid to other workers in our economy.
"We will say workers on the minimum wage must never be left behind because those who work hard to create our nation's wealth should share in it."
Liberal Democrat Business Secretary Vince Cable has also proposed setting a long-term target and Chancellor George Osborne has called for the minimum wage to rise to £7 an hour.
The minimum wage will increase by 19p an hour to £6.50 from October.