The dispute is over imposed rota changes which are said to destroy workers’ ability to spend time with their families.

In contravention of an agreement signed with the union Unite earlier this year, Muller is trying to impose a five days on two days off rota system. The changes would require all drivers to work at least one day every weekend.

The company, which made a £16.5 million profit in 2020 and forecast more in 2021, wants to impose the rota to save money when they contract third party hauliers to deliver products.

Unite general secretary Sharon Graham said: “These rota changes, which Muller has imposed despite agreeing not to, will cause havoc with our members’ family lives.

“Muller already turns a substantial profit; this is simply a greedy attempt to milk even more by attacking the workers’ work-life balance.

“Muller signed an agreement – it needs to stick to it. Instead of relying on costly outsourcing firms, Muller would save money if it recruited extra drivers directly.”

The latest round of strike action began on November 2 and ends on November 12. More strikes are set to be scheduled if the changes are not rescinded.

The workers are responsible for delivering milk, flavoured milk and potted cream to M&S, Waitrose, Sainsbury’s and Tesco stores across the country.