FORMER US presidential candidate Bernie Sanders is calling on McDonald’s to give its workers a pay rise to $15 (£11.50) an hour and allow them to form a trade union.

The Vermont senator wrote a letter to the fast food giant’s boss Steve Easterbrook on Thursday demanding it increase the minimum wage it pays its staff.

"If McDonald's raised the minimum wage to $15 an hour and respected the constitutional rights of your workers to form a union, it would set an example for the entire fast food industry to follow,” Mr Sanders wrote.

Workers in the US have been on strike this week as part of the Service Employees International Union (SEIU)-led Fight for Fifteen campaign.

McDonald’s workers were joined by caretakers, healthcare workers and other low-paid staff in this week’s action which took place in a number of US cities.

A heavy-handed police response saw 20 workers arrested in Detroit while 23 were arrested in Milwaukee on Wednesday.

But Mr Sanders said the workers’ claims were justified and highlighted the impact of low pay on McDonald’s employees.

"Today, McDonald's pays wages that are so low many of its workers need food stamps, Medicaid and public housing to survive.

“According to one study, the US taxpayer is subsidising the low pay at McDonald’s to the tune of $1.2 billion (£920 million) a year. In my view that is unacceptable.”

He had previously supported workers in their successful campaign for $15 an hour at online retail giants Amazon.

However, although the rise for workers was agreed, it emerged that it would be offset by cuts to employee shares and other incentive schemes.