By Jonathan Davies

The number of zero-hour contracts in the UK grew by more than 100,000 in the second quarter of 2015, according to the Office for National Statistics (ONS).

The ONS said there are now 744,000 people who describe their zero-hours contract as their main job, up from 624,000 in the last period last year.

It means that 2.4% of the UK's workforce is now on a zero-hours contract, up from 2% last year.

The rise comes despite widespread debate and condemnation for zero-hours contracts. In the general election campaign, then Labour leader Ed Miliband campaigned to scrap zero-hours contracts. But the government believes that zero-hours contracts are good for the majority of those working on them.

Last year the coalition government enforced stricter rules on zero-hours contracts, making it illegal for employers to prevent zero-hours workers from holding another job.

Two-thirds of the rise is from people in their job for more than a year and so the overall increase does not necessarily relate to new zero-hours contracts, ONS said.

"It could have been due either to increased recognition or to people moving on to a zero-hours contract with the same employer," the statistics agency explained.

Women made up 54% of those on zero-hours contracts, compared with 46% of men. Zero-hours contracts were common among students, with 20% of people on them being in full-time education, compared with just 3% of other workers.

Senior ONS statistician Nick Palmer said: “Both measures suggest there may have been a small trend towards more use of zero-hours contracts, although the usual margins of error associated with the surveys’ estimates mean that we cannot be certain of this. Moreover, as previously, the results from the Labour Force Survey might have been influenced by increased recognition of the term ‘zero hours contract’ among respondents.”