The Government is likely to outlaw zero hour contracts, once the findings of a review into the practice outlines how to effectively do it.

Workplace Relations Minister Michael Woodhouse is readying to abolish the practice, once he receives the findings of a review he initiated last year.

The news comes as Unite Union is locked in a negotiation battle with fast food giants McDonalds and Restaurant Brands - which owns Pizza Hut, KFC, Starbucks and Carl's Jr - to stop the contracts.

Controversial zero-hour contracts mean workers had to be available for work but had no guaranteed hours per week. Woodhouse asked officials to review the legislation late last year, amid concerns employment laws were not being used as intended.

Prime Minister John Key said if zero-hour contracts were being used in a way to discriminate against employees then that had to stop.

"But general flexibility in the labour force is also important, because there are some people who want to have that flexibility."

Casual contracts were a common practice, which did not require employees to always be available or prevent them from picking up hours elsewhere.

Woodhouse told One News it was worth banning zero-hour contracts, even if their implementation was relatively low.

"We can expect to get some good advice about that to make some changes in that bill to effectively rule out those kind of punitive provisions. "Even if it is a relatively low incidence in our employment, it's probably worth ruling them out, for the sake of certainty for those vulnerable workers."

Workers at McDonald's would strike this week, with the fast-food chain's claim it will provide secure staff hours dismissed as 'meaningless' by Unite Union.

McDonald's NZ announced Monday all employees would receive 80 per cent security of hours up to a 40-hour cap, based on the average of the previous 12 weeks.

That had "previously been common practice" when it came to scheduling in McDonald's restaurants, but would now be formally written into employment agreements, communications manager Kim Bartlett said.

Restaurant Brands - which owns KFC, Starbucks, Pizza Hut and Carl's Jr - negotiated with Unite Union last week to end zero-hour contracts by July.

But Unite Union national director Mike Treen said what McDonald's was offering was to guarantee a percentage of rostered hours, which was "radically different" to the guarantee of a percentage of hours actually worked which Restaurant Brands agreed to.

"If it's on rostered hours, it's 100 per cent at the discretion of the rostering manager - we have no control over it, we can't measure it, we can't monitor it, we can't stop managers manipulating it up and down," Treen said of the McDonald's proposal.

"It's not a meaningful offer and they are misleading the public to say it is a secure hours regime."

Unite said strikes and protests would go ahead at McDonald's, Burger King and Wendy's on Wednesday as part of an international fast food workers day of action.

The problem with zero-hour contracts was not that an employee worked no hours, but that they did not know how many hours they were guaranteed in a week, Treen said.

McDonald's proposed guarantee was no better than the status quo, as companies could roster a staff member on for less hours than they actually worked.

"The roster can be changed unilaterally from week to week - there's no guarantee in a roster, it can be made up at any time - just the same as what happens now."

"These companies always roster people for fewer hours than they need and less than they usually work to keep the workers hungry for hours and waiting at home for a phone call for extra shifts," Treen said.

Later responding to Treen's comments Bartlett said McDonald's was "committed to reaching an agreement with Unite on security of hours".

"Unite's public statements today are a distraction to our new position around security of hours; we are not surprised they have found fault with our offer and still intend to strike on Wednesday, given they already had plans in place to do so."

The fast-food chain had been in discussions about the structure of its employment contracts for several months, Bartlett said.

After a review of the way contracts were structured, Bartlett said McDonald's understood having security of hours was important to its people.

"We will continue to bargain in good faith and hope to reach a mutually acceptable agreement soon."

Labour Party industrial relations spokesman Iain Lees-Galloway said a worker's rostered hours could be a lot lower than what they had actually worked.

The McDonald's proposal could potentially still leave the employee vulnerable to roster changes for no reason.

"There's obviously a lot of pressure on the employee to stay in the manager's good books and not raise issues of workplace safety or join a union or do anything which might upset the person setting the rosters," Lees-Galloway said.

"If the guaranteed hours are based on rostered hours an employee could see their guaranteed hours fall dramatically if their rosters were deliberately manipulated to make that happen."

Lee-Galloway said it had not been a wise move from McDonald's to issue a media statement while they were still bargaining with Unite.

"I think it would have been better to reach an agreement and make their position clear with the union before they went out and made a public statement - I think that's probably where the confusion has come from, there wasn't clarity at the bargaining table before that statement was made.

"If you're bargaining in good faith its best to reach agreement to do that bargaining at the table and deal with the people at the table with you rather than going out and making statements in public before that agreement is reached."

Unite Union rejected McDonald's offer on Monday afternoon, and said it remained in dispute with McDonald's, Burger King and Wendy's.