The number of zero hours contracts used by employers has risen by one-fifth, according to the Office for National Statistics (ONS).
The ONS found that there were 744,000 people working under the controversial contracts, which do not guarantee a minimum number of hours, between April and June this year.
Zero hours contracts
This accounts for 2.4% of all those in employment, or one in 40 people in work.
This time last year there were 624,000 people on zero hours contracts, or 2% of the working population.
In a survey of employers taken before April, the ONS revealed there were 1.5 million contracts without a guarantee of hours used in January this year, compared to 1.4 million in January 2014.
The latest ONS research found that around two in 5 (41%) people on zero hours contracts want more hours, compared with 12% of other people in employment, while 12% of those on zero hours deals would prefer a different job with more hours (compared with 2% for other people in employment).
The figures also show that people on zero hours contracts are more likely to be women, in full-time education or in young or older age groups when compared with other people in employment.
TUC General Secretary Francis O’Grady said: “Zero hours contracts are a stark reminder of Britain’s two-tier workforce.
“People employed on these contracts earn £300 a week less, on average, than workers in secure jobs.
“I challenge any minister or business leader to survive on a low-paid zero hours contract job, not knowing from one day to the next how much work they will have.”
Zero hours contracts became a central political issue in the run up to this year’s election, with the Labour party pledging a crackdown on their use and the promise of a regular contract after 12 weeks.
The coalition Government has already removed employers’ ability to include “exclusivity clauses” from zero hours contracts, but, in practice, anyone on a contract can still be refused work.
Laura Gardiner, senior policy analyst at think tank Resolution Foundation, said: “It is clear that this form of working is not fading away as our employment recovery gains ground.
“While it’s true that some people value the flexibility offered by zero hours contracts, for many they bring deep insecurity.
“Policy makers must act to ensure that the benefits of labour market flexibility are balanced appropriately with protecting workers’ rights.”