ED Miliband will today unveil a key plank in his bid to win power by announcing that a future Labour government will boost the national minimum wage significantly to tackle what he believes is the continuing scandal of low pay in Britain.

While the Labour leader will not give a specific target figure — the full adult rate will rise this October from £6.31 to £6.50 per hour — he will insist a Labour government will seek to restore the ambition of the national minimum wage his party established 15 years ago so that the level gets much closer to average earnings.

"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," Mr Miliband will say.

"It is time to raise our sights again because Britain can do better than this. The next Labour government will restore the link between hard work and building a decent life for your family."

The Labour leader is due to speak at the publication of an independent report on low pay by Alan Buckle, the former deputy chairman of KPMG International, which he commissioned in 2013.

This shows there are 5.2 million workers on low pay, up from 3.4 million in 2009, representing one in five of all workers and one in three of women at work.

It says the cost of low pay to government finances is estimated at £3.2bn.

Poor enforcement in some sectors means more than 250,000 people are estimated to earn less than the minimum wage, while the UK has both higher levels of low pay and lower levels of productivity than many of its international competitors.