Labour and the Conservatives opened up a new battlefield over jobs yesterday (FRI) as former Tory leader Iain Duncan Smith claimed 'zero-hours contracts' should be rebranded not scrapped.

Labour accused the Work and Pensions Secretary of being out of touch after he suggested the controversial contracts needed a makeover.

The row came just hours after David Cameron claimed Labour would preside over the loss of one million jobs if it win May's General Election.

Newly released official figures also showed that unemployment in Scotland actually rose over the last quarter.

The numbers out of work increased by 9,000, to 167,000 between December and February, according to the Office for National Statistics (ONS).

Ed Miliband has pledged that a Labour government would ban exploitative zero-hours contracts.

Mr Cameron recently controversially admitted that he could not live on such a contract, which have been condemned by unions for failing to offer guaranteed hours or wages.

But the Coalition Government has argued that the flexibility they offer is helpful to some workers.

Asked about the issue, Mr Duncan Smith suggested that zero-hours contracts needed a name change.

He said: "Zero-hour contract is badly named - I don't know whoever came up with that idea. It should be named the flexible hours contract because the people that actually use that contract are, for the most part, people who have caring responsibilities, students, people who can't guarantee hours, fixed hours, over a series of weeks, but who are able therefore to flex their work and take the work as necessary."

Rachel Reeves, the shadow work and pensions secretary, said his comments showed how "completely out of touch" the Conservatives were.

"We don't need to rename exploitative zero-hours contracts, we need to ban them," she said.

"For too many people zero-hours contracts leave people without a regular income and not knowing from one day to the next how much work will be coming in. It's insecurity dressed up as flexibility.

"David Cameron said he couldn't live on a zero-hours contract but the Tories are happy for working people to be stuck in low paid zero-hour contract jobs."

Separately, Mr Miliband also pledged to put an end to what he described as the "scandal" of long-term unpaid internships.

He claimed the current system was rigged in favour of wealthy families who can afford to support their children for months on end while they work for free to secure jobs in competitive fields such as law and finance.

Earlier Mr Cameron said that a Labour government would put one million jobs at risk.

He said: "Labour are threatening big tax hikes on businesses. More regulation.

"Undermining our economy with more borrowing and more debt. This is the sure-fire way to destroy jobs, not create them."

He also hailed what he described as the jobs "miracle" that has taken place since the coalition government came to power in 2010.

The Chancellor George Osborne also welcomed praise on the economy from the head of the International Monetary Fund (IMF) Christine Lagarde.

Ms Lagarde said the strategy pursued over the last five years was "clearly delivering results" when compared to other European economies.

The official figures show that the number of people in employment in Scotland also rose, by 3,000 during the three months between December and February.

The number in work is up by 46,000 over the past year, at 2,615,000, while the Scottish employment rate is 74.2 per cent , above the UK average of 73.4 per cent.

Fair Work, Skills and Training Secretary Roseanna Cunningham said: "I am pleased that female employment level has increased significantly in the past year. We will continue to do everything we can to ensure women have the same opportunities in the labour market as their male counterparts, and have access to quality sustained work in careers they choose.

"Youth unemployment figures continue to improve. Our ambition however, is to reach and move beyond pre-recession levels through the implementation of our long-term youth employment strategy.

"Whilst Scotland continues to have a higher employment rate than the UK as a whole, today's figures show a slight increase in unemployment on the previous quarter.

"This can be explained, in part, by falling levels of economic inactivity, which is now at an all-time low, as more people join the labour market and start looking for work."

Scottish Liberal Democrat leader Willie Rennie said: "This demonstrates why Scotland needs Liberal Democrats in government to anchor the economy in the centre ground.

"Employment levels have hit new records today, with almost three-quarters of working-aged people now in work.

"With wages now rising continuously faster than inflation, living standards are rising too.

"The role of the Liberal Democrats in government has been crucial to promoting economic stability and a strong recovery."