The Government is set to spend more than £5 billion more on tax credits than it expected over the five years of this Parliament, according to new figures.

Labour blamed the overspend - revealed in figures from the House of Commons Library - on rising levels of low pay, which have left more people reliant on in-work benefits.

Shadow work and pensions secretary Rachel Reeves predicted that the bill for in-work benefits - including housing benefit - will continue to rise faster than inflation after next year's general election.

The new figures show that a total of £157.5 billion has been spent on tax credits in the five years 2010/11 to 2014/15. This is some £5.4 billion more than the £152.1 billion predicted by the Office for Budget Responsibility in November 2010.

The OBR anticipated total spending on tax credits would peak at £30.8 billion in 2012/13 and remain at roughly that level to the end of the Parliament. In fact, the bill reached £31.9 billion in 2011/12 and has remained above £31 billion annually ever since.

In a speech in east London highlighting what Labour claims is waste in the welfare budgets, Ms Reeves is due to say: "Today we are publishing new independent research which shows that David Cameron's Government has spent £5 billion more than it planned on tax credits over the course of this Parliament.

"This huge overspend is the result of the Tory Government's failure to tackle rising levels of low pay and job insecurity. This failure means spending on in-work benefits - including housing benefit - is set to continue rising in real terms well into the next parliament.

"This is yet another example of Tory welfare waste: billions more of taxpayers' money spent on in-work benefits, 900,000 people waiting for a combined 118,000 years in a huge backlog for sickness and disability benefit assessments. And the shambles of Universal Credit leading to huge delays and over £130 million of taxpayers' money already wasted on failed IT."

A Conservative spokesman said: "This is desperate stuff from Labour - the party which let the benefits bill double, including a 340% rise in tax credit spending.

"What's more, they've opposed every single step we've taken to put things right. No-one will trust a word Labour say when it comes to getting welfare spending down.

"While Labour remain the welfare party, Conservatives are bringing benefits back under control.

"Working through our long-term economic plan, our welfare reforms are set to save £50 billion over the course of this Parliament. More importantly still, over 1.7 million more people are in work and have the security of a pay packet at the end of the month. A vote for Labour at the next election will put all of that at risk."