Freshfields Bruckhaus Deringer and Cravath Swaine & Moore have picked up lead roles on US medical giant Johnson & Johnson's attempted £7bn bid for Smith & Nephew.

Freshfields has been fielding a team led by corporate partners Barry O'Brien and Ben Spiers advising longstanding client Smith & Nephew, which has not formally confirmed or denied this month's reported takeover approach.

The magic circle law firm is a regular adviser to Smith & Nephew. In the past, the UK hip and knee replacement maker has also turned to Slaughter and May, Ashurst and Pinsent Masons for advice.

Cravath, meanwhile, has been advising Johnson & Johnson on its so far unsuccessful bid, with corporate partner Robert Townsend leading the team.

Both firms are understood to be providing ongoing advice to the companies as reports emerged last week that Johnson & Johnson could up its takeover offer. It has been reported that the company's initial offer was rejected before Christmas on the basis that the price was too low.

A number of additional law firms could win roles in relation to the deal if other companies consider bidding for the British company.

One City partner commented: "Smith & Nephew's share value will continue to rise because of the increased interest in the company, as well as the strong growth opportunities in the orthopaedics market. More offers are certain to follow."

The attempted bid has reignited concerns about the number of large British companies falling into foreign ownership.