Supermarket workers in 12 Oxfordshire stores face an uncertain future after the Co-op announced it might have to sell shops following its £1.57bn buyout of its rival chain Somerfield today.

A Co-op spokesman said that the Office of Fair Trading would have to investigate whether owning two stores in a town or village was a breach of competition laws.

The Co-op and Somerfield currently have one store each in Abingdon, Carterton, Summertown, Headington, Chipping Norton and Witney.

When Morrisons bought Safeway in 2003, it was forced to sell off 53 stores nationally in order to comply with competition laws.

Co-op spokesman Lizzie Morgan said: "There are going to be some competition issues which the OFT will have to investigate.

"We may have to divest some stores, but we can't say if any will be in Oxfordshire until an investigation is done by the OFT."

She added: "The Co-op is confident it will be able to work through the merger with a minimum loss of jobs, but we can't say which stores are going to be safe at the moment."

The Co-op/Somerfield chain will run about 3,000 grocery stores nationwide, generating annual sales of about £8bn