Allen & Overy (A&O) has topped the rankings for debt capital markets work for banks for the first half of 2006, overtaking last quarter's leaders, Linklaters.

According to statistics compiled by Thomson Financial, A&O stands well ahead of second-placed Linklaters for international debt advice to banks ranked by deal size. The firm advised on 298 issues worth a total value of $159.6bn (£85.9bn) compared with Linklaters' 226 worth $140.6bn (£75.7bn).

Sidley Austin maintained pole position advising the issuers on the global international debt table, advising on deals worth $91.8bn (£49.4bn). A&O has climbed two places from last quarter to second place.

On the equity capital markets tables, Cleary Gottlieb Steen & Hamilton and Linklaters are battling for first place, with the former topping the tables for issuer roles, accumulating a total of $11.5bn (£6.2bn) against the latter with $9.7bn (£5.2bn). Ranked by manager roles, the positions are reversed, with Linklaters advising on 37 deals worth a total of $18.9bn (£10.2bn) – well ahead of Cleary advising on nine deals worth $9.7bn (£5.2bn).

A&O capital markets partner Boyan Wells said: "The leading firms are well ahead in the established markets, but when it comes to the newer markets, such as collateralised debt obligations, it is not as well defined. They are all new skills and clients expect law firms to know what they are doing, not to have to teach them."