Tesco is Britain's biggest private sector employer with a staff of over 300,000.

Unite said it was recognised at four distribution centres with about 1,000 members who deliver to Tesco stores across the UK.

"While the reports centre on job losses in-store, such as at the bakeries and deli counters, we still need to know what this could mean for our members," said Adrian Jones, Unite national officer for retail distribution.

The Mail on Sunday reported that up to 15,000 jobs could be put at risk by the changes, which are likely to affect the majority of Tesco's 732 larger stores.