TENS of thousands of people have signed a petition challenging Iain Duncan Smith to live on just £53 a week.

It follows claims by the former Conservative leader he could survive on just over £7.50 a day – if he had to.

The Welfare Secretary was defending the Coalition's welfare reforms, which churches and charities warned could leave many on the breadline.

Asked if he could live on just £53 a week, a figure slightly lower than that paid to out-of-work under-25s, Mr Duncan Smith said: "If I had to I would."

Within hours, thousands signed a petition urging Mr Duncan Smith, who cites a visit to Easterhouse in Glasgow as the inspiration for his political philosophy, to put his money where his mouth is.

The petition comes amid growing attacks on the Government's welfare reforms. Today, Chancellor George Osborne will use a speech to defend changes to the tax and benefit system. He will also pledge that "this month we will make work pay".

However, Labour dubbed yesterday the beginning of "black April".

A series of changes have already come into force or are due to in the coming weeks, including cuts to benefits for council tenants with a spare bedroom.

As a Cabinet minister, Mr Duncan Smith earns more than £1500 a week. The petition calls on him to live on benefits of £53 a week for at least one year.

By yesterday evening, more than 35,000 people had signed.

If he accepted the challenge it would not be the first time that Mr Duncan Smith has swapped a comfortable lifestyle for a more challenging one.

In 2010 the Cabinet minister, estimated to be a millionaire, took part in a Channel Four documentary in which he lived on an estate in London.

Alongside his claim he could live on £200 a month, Mr Duncan Smith also defended the Coalition's decision to raise many benefits by just 1%, far below the rate of inflation.

He said: "The 1% restriction to the rise in benefits is still a 1% rise. If you were sitting in Ireland or Portugal, they are actually seeing real cash cuts."

A spokesman for the Department for Work and Pensions declined to comment.

The Chancellor will today say that for too long "people who did the right thing – who get up in the morning and work hard – felt penalised for it. I want every penny of the money [people pay in taxes] to be spent on the things that matter - a better NHS, good schools and policing, strong defence, and decent pensions. Not on paying the interest on the national debt."

Chris Leslie, Labour's shadow Treasury minister, pointed to the Coalition's decision to cut the top rate of tax from 50p to 45p.

He said: "George Osborne needs to explain how it can be fair to give a £3 billion tax cut to the very richest, while millions of working families on middle and low incomes pay the price for his economic failure."

The SNP described yesterday as Westminster's "day of shame".