New York firm Curtis Mallet-Prevost Colt & Mosle is two months away from a merger with what is believed to be a 30 to 50-lawyer City practice.
The firm last week added a six-lawyer Milan practice - Studio Legale Gilioli - to its network of international offices and managing partner George Kahale said he was close to bringing an English firm on board as well.
"We are in focused negotiations with one particular law firm," he said, "and if all goes well I expect a decision within two months."
Curtis will merge its existing three-lawyer London office - established five years ago - into the UK practice.
The 180-lawyer firm, which is big in cross-border financing and keen to expand internationally, particularly in France and Latin America, also has offices in Frankfurt, Paris, Hong Kong, Mexico City and Oman.
The Milan office will be known as Curtis Mallet-Prevost & Gilioli and will be operated and managed by US-qualified partners Eric Gilioli and Carl Ruggio and affiliated with five Italian tax specialists.
Kahale said of the Milan office: "We will look to capitalise on the firm's Latin American and Middle Eastern expertise in view of the large volume of trade between Italy and those areas."
Kahale recently acted as lead counsel in the US$1.52bn financing of the Pemex Cadereyta Refinery in Mexico - the largest ever such financing in Latin America.