The number of workers on zero-hours contracts has increased by 104,000 to 801,000.
Figures from the Office for National Statistics (ONS) showed that 2.5% of the employed UK workforce were on zero-hours contracts in the quarter to last December, up from 2.3% in the same period of 2014.
The data showed there were around 1.7 million contracts that did not guarantee a minimum number of hours in November, confirming that many workers are on more than one zero-hours contract.
ONS statistician Nick Palmer said: “This latest figure is rather higher than the 697,000 people who said they were on these contracts in late 2014.
“Though at least some of this increase may be due to greater public recognition of the term zero-hours contract, there’s also nothing to suggest this form of employment is in decline.”
People on zero-hours contracts were more likely to be young, part-time, women, or in full-time education when compared with other people in employment.
On average, someone on a zero-hours contract usually worked 26 hours a week. Around one in three people on a zero-hours contract wanted more hours, with most wanting them in their current job, as opposed to a different job which offered more hours.
In comparison, 10% of other people in employment wanted more hours, said the ONS.
TUC general secretary Frances O’Grady said: “Zero-hours contracts may be a dream for cost-cutting employers, but they can be a nightmare for workers.
“Many people on zero-hours contracts are unable to plan for their future and regularly struggle with paying bills and having a decent family life.
“The so-called flexibility these contracts offer is far too one-sided. Staff without guaranteed pay have much less power to stand up for their rights and often feel afraid to turn down shifts in case they fall out of favour with their boss.
“The European Union is proposing better rights for zero-hours workers – another reason why workers should be worried about the risks of Brexit.”
Research by the TUC shows that average weekly earnings for zero-hours workers are £188, compared to £479 for permanent workers.
The 801,000 figure is the highest since records began on zero-hours contracts, under which workers do not know from one week to the next how many hours they will be offered.
Jon Ingham of jobs site Glassdoor said: “The most common reason that unemployed people turn down zero-hours contracts is the need for a guaranteed level of income to make this a viable alternative to receiving unemployment benefit. These contracts favour the employers over the employees.
“With 38% of these contracts held by 16 to 24-year-olds, it means there is now a significant proportion of the young workforce without guaranteed incomes.
“This pay-as-you-go employment causes issues and judging by the comments on Glassdoor, this is not a preferred choice of employment in the long term.”
Owen Smith, shadow work and pensions secretary, said: “The scale of the crisis of insecure work under the Tories is getting worse with every passing week.
“Before the election they promised to act on zero-hours contracts, but these numbers show that was nothing more than words. Spiralling numbers of British workers cannot be certain where their next day’s work is coming from, making it virtually impossible to plan finances and family life.”
Laura Gardiner, of the Resolution Foundation, said: “As a share of the workforce, the number of people on zero-hours contracts continues to rise despite the record employment rate and the long-overdue pay recovery last year. It’s increasingly clear that zero-hours contracts are here to stay, whatever the economic weather.
“While some workers value the flexibility they provide, others struggle to manage their fluctuating pay levels week by week and find it hard to budget and put any money aside as savings. This explains why one in three workers on a zero-hours contract want more hours.
“While zero-hours contracts still make up a comparatively small, albeit growing, part of the labour market, it is still crucial that policy makers consider the effect of unstable employment on both workers and the economy, while ensuring the employment rate continues to reach record highs.”