LONDON, UNITED KINGDOM (REUTERS) - Fast food giant McDonald's is hit by its first UK strike as staff take action in a row over zero-hours contracts.

"They didn't want to hear us before, so now we are going to be as loud as we can to make sure they can hear us this time," said striking McDonald's worker Stephanie.

Taking a bite out of McDonalds public image, this is one of two UK restaurants where workers have gone on strike, for the first time ever.

Around 40 staff are protesting over pay and work conditions.

They're demanding an end to zero-hours contracts and a minimum wage of £10 (S$17.53) per hour.

McDonalds argues the dispute is over internal grievance, not pay or contracts.

Tom Holliday who gets £7.55 an hour - the minimum wage for a worker over 25 in Britain.

"Every single one deserves more," said Holliday.

McDonald's reported revenues of $24.6 billion in 2016, while Chief Executive Steve Easterbrook earned $15.4 million.

Although not unionised, the workers are being backed by the the Bakers, Food and Allied Workers Union.

It's long highlighted what it calls 'exploitative' zero-hours contracts, which don't provide set hours annual leave, sick pay or pension.

McDonald's employees around 85,000 people in the UK.

It's currently in the process of offering all staff the chance to switch from a zero-hours contract, to one with guaranteed hours.

So far it says 86 per cent had chosen to remain on a flexible contract.