There has been controversy about firms using zero-hours contracts but not allowing staff to work elsewhere.

McDonald's has been trialling the move in 23 company-owned and franchise outlets.

During the trial only around 20% of the staff chose to move to fixed hours contracts, the company said in a statement.

Paul Pomroy, McDonald's UK chief executive officer, said: "The vast majority of our employees are happy with their flexible contracts, but some have told us that more fixed hours would help them get better access to some financial products.

"Thanks to the support of our franchisees, we are able to respond to our people's needs, and will begin to roll out fixed hours' contracts, including new joiners, across the course of the year," he added.

McDonald's has a UK workforce of more than 115,000, the majority of which are on zero-hours contracts.

Paul Maloney, the GMB union's southern region secretary, said: "Workers at McDonald's should be offered up to 40 hours of work a week, and permanent contracts to include annual leave, sick pay and a pension scheme.

"The government has been examining possible changes to make precarious employment more secure."

Profits get fatter

Meanwhile, investors got a taste for McDonald's shares after the fast food chain reported better-than-expected profits in the first quarter.

McDonald's said profits grew by 8% to $1.2bn (£950m), helped by cost cuts, Big Mac promotions and an expansion of its All-Day Breakfast.

Its shares rose more than 5% to hit a record high.

Sales declined for the eleventh straight quarter, but fell by less than analysts had expected.

The company's chief executive, Steve Easterbrook, unveiled new plans last month to win back and retain customers.

Mr Easterbrook said the first-quarter results showed McDonald's had a "sense of urgency across the business".

Revenue fell 4% to $5.68bn, although that was partly due to the sale of restaurants to franchisees as part of Mr Easterbrook's turnaround strategy.

Sales were higher than expected after growth in China and the UK, as well as the launch of its All-Day Breakfast in Canada following a similar rollout in the US in 2015.

Shares in McDonald's have now risen about 15% this year, giving the firm a market value of $115bn.