Lovells and US energy leader LeBoeuf Lamb Greene & MacRae have bagged the main advisory roles on the € 699m (£462m) sale of UK oil and gas company Intrepid Energy North Sea to Petro-Canada. LeBoeuf is acting for Intrepid and Lovells for Petro-Canada.

Corporate partner John Cooper, who heads Lovells' energy and utilities team, said the transaction strengthens a preexisting relationship with Petro-Canada.

"We have had some good energy deals in the past, but this is certainly a biggy," he told Legal Week. "We are trying to build the corporate aspect of our energy group."

The current deal comes amid an active period for Lovells' energy practice, with the firm acting last year for key client Statoil on its $740m (£404m) acquisition of BP's interests in the In Salah and In Amenas projects in Algeria.

Cooper was assisted on the Intrepid deal by Lovells partners Richard Tyler and oil and gas veteran Michael Stanger, with the pair advising on energy-specific aspects of the transaction.

Chris Hearns, corporate finance manager at Intrepid, said that the company has a long-standing relationship with LeBoeuf partner Keith Hughes, who is heading the deal for the New York firm.

"It is certainly likely to be the largest deal I will work on this year," said London-based Hughes, adding that work to get to this stage has been going on for two years. He was assisted by a team of six, with Ben Donovan the lead associate.

Herbert Smith advised Intrepid financial adviser JP Morgan. Last year, the top 10 London firm also advised JP Morgan on a £359m secured credit facility to provide financing for the development of Intrepid's interest in the Buzzard Field, the largest UK North Sea oil field discovered in more than a decade, which Intrepid owns a 29.9% stake in. The deal will see Petro-Canada purchase Intrepid Energy's interest in Buzzard Field, which is located 100km northeast of Aberdeen, along with nearby potential exploration areas. The transaction, which is still subject to shareholder approval, is expected to complete this month.