By Jonathan Davies
Businesses in the UK used 1.8 million zero-hour contracts in August 2014, according to the Office for National Statistics (ONS).
The total figure, taken during the first two weeks of August, grew from 1.4 million when figures were first collected in a two-week spell in January.
However, it is difficult to compare the figures because the summer increase is likely to be as a result of seasonal industries using zero-hour contracts for that season.
Zero-hour contracts have become a contentious issue over the past year. Some are against the no guarantee of work, but the government says that they work well for many people and are a vital party of the employment market.
A separate survey by the ONS found that 697,000, or 2.3% of all people in employment in the UK, said they were on a zero-hour contract as their main job between October and December 2014.
The figure is an increase from 586,000 in the same period in 2013. However, the ONS said that this may not necessarily be due an increase in the number of people on zero-hour contracts, but people becoming aware that they are on one.
The statistics agency said people were more likely to be aware that they were employed on a zero-hour contract if they had been in the job for more than a year.
TUC general secretary Frances O'Grady said: "Zero-hours contracts sum up what has gone wrong in the modern workplace. They shift almost all power from the worker and give it to their boss."
But Business Secretary Vince Cable said: "Zero-hours contracts are valued by many employers and individuals who want flexibility in the hours they work, such as students, people with caring responsibilities and those who want to partially retire.
"However, historically there has also been some abuse in these types of contracts."