The number of workers on zero-hours contracts could be one million - four times as high as official estimates, according to new research. Such workers are on call to work when needed by bosses but employers do not have guarantee any hours.
Business Secretary Vince Cable has ordered a review of zero-hours contracts, saying little is known of the impact they have on employees.
He said: "For some these can be the right sort of employment contract, giving workers a choice of working patterns. However for a contract that is now more widely used, we know relatively little about its effect on employers and employees.
"There has been anecdotal evidence of abuse by certain employers - including in the public sector - of some vulnerable workers at the margins of the labour market.
"Whilst it's important our workforce remains flexible, it is equally important that it is treated fairly. This is why I have asked my officials to undertake some work over the summer to better understand how this type of contract is working in practice today."
The government is looking into zero hours contracts as new research says the number of people working such contracts could be one million.
Opinion varies dramatically among both workers and employees when it comes to zero hours contracts, as ITV News viewers demonstrate.