ANKARA 

The leader of the center-left opposition Labour Party announced Wednesday that workers employed under zero-hours contracts would be legally entitled to a contract after three months under a future Labour government.

Ed Miliband made his comments at a campaign event in Yorkshire, two days after the U.K. general election campaign officially began.

Zero-hours contracts do not guarantee workers regular or minimum work hours.

They have so far been central to Labour attacks on the center-right Conservative Party, which is the senior partner in the coalition that has governed the U.K. since the 2010 general election ended in a hung parliament.

Labour’s new policy would affect 90 percent of zero-hours contracts, but not ban them entirely.

The policy aims to puncture coalition claims of good job growth by making the case that many of these jobs are insecure.

A report published in late February by the U.K.'s Office for National Statistics, or ONS, estimated that there were nearly 700,000 workers on zero-hours contracts in their main job between October and December 2014. This was an 18.9 percent increase from the previous year’s figure of 586,000.

As employees often work more than one job, the ONS estimate found there were 1.8 million contracts that “do not guarantee a minimum number of hours” in 2014, up from 1.4 million in the previous year.

In 58 percent of these cases, workers had been with their current employers for more than a year. Those on zero-hour contracts worked 25 hours per week on average.

During the first of four leadership debates on March 26, Conservative Prime Minister David Cameron admitted that he could not personally live on a zero-hours contract.

However, he defended the contracts by saying that some workers, such as students, enjoy the flexibility they provide.

Miliband seized on this claim at his campaign event, sarcastically saying: “People really want to be uncertain – about whether they’ll be able to pay the energy bill or not. They really want to be insecure – not knowing how much food they’re going to be able to put on their family’s table.”

“We need a fairer system that guarantees zero-hours workers decent rights at work and stops them from being treated like second-class employees,” Frances O’Grady, general secretary of the Trade Union Congress, said in a statement.

The TUC is a federation of trade unions in England and Wales.

Director-General of the Confederation of Business Industry John Cridland said in a statement that “the U.K.’s flexible jobs market has given us an employment rate that is the envy of other countries…Of course, action should be taken to tackle abuses, but demonising flexible contracts is playing with the jobs that many firms and many workers value and need.” The CBI is a lobby group for British businesses.

The U.K. general election will take place on May 7, 2015.