Allen & Overy (A&O) and Clifford Chance (CC) have taken the top positions in tables of legal advisers representing financial advisers on European M&A deals in 2005.

The bespoke rankings, compiled by Mergermarket for Legal Week, show A&O as the number one firm by value and CC as top of the volume rankings in a table of the top counsel to financial advisers on European M&A deals last year.

A&O advised on 14 deals in 2005, worth a total of £62.5bn and was one of a cluster of firms advising on deals worth more than £40bn. The other firms in the top five were Skadden Arps Slate Meagher & Flom (£58.7bn), CC (£55.4bn), Sullivan & Cromwell (£52bn) and Gibson Dunn & Crutcher (£41.2bn).

A key deal for A&O was advising UBS on the £28.9bn Gas Natural/ Endesa bid. UBS is providing financial advice to Gas Natural.

Richard Cranfield, A&O's head of corporate, said: "We do not have a strategy for focusing on investment banks over corporates, but we have always had strong relationships with the investment banks and last year we had a good strike rate on the major deals."

The tables are believed to be the first of their kind and demonstrate the strong standing of the UK's finance-focused firms alongside US firms with the investment banks.

A&O's result contrasts with its position in a table of legal advisers taking the lead role advising corporates on European M&A deals in 2005. In that research, A&O came sixth, working on deals worth £32.7bn, with Freshfields Bruckhaus Deringer topping the rankings having advised on deals worth £131.2bn.

CC, meanwhile, led the bank rankings in terms of volume, advising on 26 deals worth £55.4bn.

Second placed by volume was Dewey Ballantine, which advised on 21 deals, while Sullivan came third with 20, Linklaters fourth with 15 and A&O fifth with 14 deals.

Richard Morrissey, head of Sullivan's European corporate practice, said: "Our result reflects a number of strong relationships we have with a number of investment banks, as well our strong position advising principals."