Brewer Wolverhampton and Dudley yesterday launched a High Court action against Pubmaster, the Hartlepool pubs group bidding £453m for the business.

W&D claims Pubmaster leaked sensitive commercial details of its brewery business to competitors and is seeking an injunction against the company.

Pubmaster is hoping to sell on the brewery business, which makes Pedigree ale and Harp lager, if its bid is successful, while keeping W&D's 1,600 pubs.

A Pubmaster spokesman said the company had only passed on basic information such as the address of W&D's four breweries and the acreage of each site.

The case comes as the deadline for W&D's defence of Pubmaster's 480p per share bid approaches. W&D said it had received no satisfactory undertakings from Pubmaster that further confidential information would be not given to its competitors.

Chairman David Thompson said: "We have no option but to prevent any further misuse of our data."

The Pubmaster spokesman said: "We have complied with all the confidentiality agreements we have with them."

Pubmaster launched its hostile bid for W&D on June 4. Earlier this month it showed just 3.7 per cent of W&D's shareholders had backed it.

It intends to return £200m to investors over the next two years.

In a statement to the Stock Exchange yesterday, Wolves said detailed confidential information relating to its brands division was disclosed by Pubmaster to at least two of its principal competitors - Bass and Carlsberg-Tetley.

W&D said the disclosures - which included details of product costs and marketing activity - were in breach of the terms of confidentiality agreements entered into between Pubmaster and W&D, and were potentially damaging to Wolves' competitive trading position.

Pubmistress, the holding company of Pubmaster, said it considered that it had complied with the terms of the confidentiality undertaking and had provided W&D with a complete list of all parties to whom information was given.