Cable vow on zero hours 'abuse'
Ministers said they wanted to discover if "unscrupulous" employers might try to find a way of avoiding the ban by offering just one hour of work.
Business Secretary Vince Cable said: "We are tightening the screws on rogue employers who try to abuse workers on zero hour contracts.
"We are looking closely at any potential loopholes that could arise from a ban, to ensure that these are closed off and no one can get round the new law. We are also ensuring there is access to justice for workers treated unfairly.
"The evidence shows that the vast majority of zero-hour contracts have been used responsibly by many businesses for many years, but unfortunately we know that some abuse does take place.
"This is why we are bringing in new laws to ban the use of exclusivity clauses in zero hours contracts, which currently stop employees getting other jobs if they need to top up their income.
"We want to give individuals the chance to find work that suits their individual circumstances whilst also giving employers the confidence to hire and create new jobs".
The Government also announced that business representatives and unions will work together to draw up codes of practice to help guide the fair use of zero hours contracts.
The coalition has responded to calls for zero hours contracts to be outlawed, by planning to ban exclusivity clauses, under which employers prevent people from working for someone else.
A recent study estimated that over 620,000 workers are employed on a zero hours contract, which do not guarantee work from one week to the next.
TUC general secretary Frances O'Grady said: "While it's reassuring to see that Vince Cable is determined there should be no loopholes for employers who might try to get around the exclusivity ban when it becomes law this autumn, in truth there is much more the Government should be doing.
"Many new jobs are being created, but far too many are of the zero-hours kind - where workers can have no idea from one week to the next how many hours or how much pay they're likely to get.
"This uncertainty means it's hard for people to plan their household budgets and make their money go far enough even to cover their everyday expenses."
Tim Thomas, head of employment policy at EEF, the manufacturers' organisation, said: "To date Government has taken a balanced approach to the regulation of zero hours contracts which should continue.
"For manufacturers, they provide much needed workplace flexibility and access to skills whilst, for workers, they offer well paid and flexible opportunities.
"Companies will want to see any future loopholes that could be used to avoid the new laws closed to ensure fairness. But, Government must at the same time avoid inadvertently implementing an outright ban."
Shadow business secretary Chuka Umunna said: "We have seen a rising tide of insecurity in the workplace since David Cameron came to office, with his Government watering down the rights at work of every working person in this country.
"So it is unsurprising the Government has put forward the minimum it thought it could get away with to deal with exploitative zero hours contracts. Their measures simply do not go far enough."