A workers' strike at fast food outlets across some of New Zealand's biggest CBDs could spread to regional centres such as Tauranga, as the row over zero-hour contracts comes to a head.

McDonald's and Wendy's staff are striking today in Auckland, Wellington Christchurch, Dunedin, and Palmerston North, and the Unite Union haven't ruled out further action which could include the Bay of Plenty.

McDonald's workers in Tauranga may be the next to strike. Photo: File.

The union are currently negotiating with fast food operator Restaurant Brands - which owns Pizza Hut, KFC, Starbucks and Carl's Jr - to put a stop zero-hour contracts.

The controversial conditions mean workers have to be available for work, but are not given any guaranteed hours per week.

'We will be taking action in the smaller centres in the coming weeks if there is still no movement,” says Unite Union national director Mike Treen today. 'But at the moment it is only where we have organisers.

'We've got members down there asking about when they can take action, but we don't like to call people out if we can't protect them when they go back.

'It's a bit difficult to get them to do it on their own without a helping hand, and they are under a bit of pressure too. So we want to make sure we have got an organiser in the field, If that happens.”

Restaurant Brands negotiated with Unite last week to end zero-hour contracts by July, and McDonald's counter offer on Monday has been described as 'meaningless” by the union.

McDonalds says all employees will receive 80 per cent security of hours up to a 40-hour cap, based on the average of the previous 12 weeks.

The McDonalds offer is a guarantee of a percentage of rostered hours, not a guarantee of a percentage of hours actually worked – which is what Restaurant Brands agrees to, says Mike.

Rostered hours are 100 per cent at the discretion of the manager, and cannot be measured or monitored. Nor can the union prevent managers manipulating them.

The argument is not that an employee works no hours, but that they do not know how many hours they are guaranteed in a week.

Unite state that McDonald's guarantee is no better than the status quo, as companies can roster a staff member on for less hours than they actually work.

'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,” adds Mike in Stuff Business this week.

'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.

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

Today's strikes and protests are part of an international fast food workers day of action.