Co-operative Group may axe staff numbers by more than a third at c-store business Alldays' Hampshire head office, as the recently acquired chain is integrated.
Alldays' departing chief executive, Stuart Lawson, said a collective consultation exercise has begun at the Eastleigh HQ that may result in more than 100 of the 300 staff there being made redundant.
Nothing has yet been finalised, but jobs could go across a spectrum of head office functions, including buying, marketing, property and accounting.
Co-operative Group is likely to unify departments and run them from its Manchester nerve centre.
Lawson said: 'At the end of the day, people are interested in how they're going to be looked after when they go. We are explaining the decision and discussing the terms on offer.'
A spokesman for Co-operative Group said: 'We are still going through category by category what the implications of the integration will be.'
He said that any transfer of staff from Alldays head office to Co-op's is likely to be a phased process over the course of a year. A decision on whether Co-op will retain the Alldays head office has not been made.
Lawson is to be replaced at Alldays by Neil Braithwaite, Co-operative Group's general manager for retail finance at present.
The pair are working together on the merger until Lawson leaves the business at the end of April, after the integration plan has been presented to the Co-op board.
Co-op acquired 600-strong Alldays in October in a deal worth£131 million.