The Office of Fair Trading has placed an ad in a trade magazine to try and find the source of a mystery complaint against Robert Wiseman Dairies.

Wiseman said it feels confident that the complaint to the OFT is not linked to the continued investigation into the company's role in the Scottish milk industry.

A spokesman for Wiseman told Grocer Today: "Given the fact we talk to the OFT on a weekly basis I am confident it would have tabled it by now."

He added that he anticipates the OFT enquiry will be drawn to a close "very shortly now".

The dairy group has been under investigation since it - together with three other Scottish dairies - was raided by OFT investigators in May 2001 on suspicion it may have abused its monopoly of the Scottish milk market.