Allen & Overy (A&O) is set to launch its first Latin American office within weeks, it has emerged, as growing numbers of international law firms look to make their mark in the region.

The firm is awaiting regulatory approval for its new base in Sao Paulo with the licence expected to come through by late September.

Latin America practice group member and project finance partner Robert Kartheiser, currently based in New York, is set to oversee the Brazilian initiative, although it is unclear whether or not he will relocate.

The news comes as magic circle rival Clifford Chance (CC) also looks to expand its presence on the ground in Brazil.

CC office head Anthony Oldfield has been stationed there full time for a month, having previously split his time between Sao Paulo and New York. The branch has around 15 lawyers in Brazil but is expanding further with David Evans, joint head of CC's Americas energy & projects group, set to relocate from Washington DC later this month.

He will become the second partner in the office alongside Oldfield who took up the position as office managing partner from Stephen Hood in September 2007 - when Mayer Brown hired Hood to launch its own offering in Brazil's biggest city.

The expansion at A&O and CC comes as a number of international firms have stepped up their efforts in Latin America - with Brazil the key target - despite local bar rules prohibiting foreign lawyers from practising local law.

US firms entering within the last year also include Skadden Arps Slate Meagher & Flom, which opened in Brazil earlier this summer, and Proskauer Rose. Simpson Thacher & Bartlett is planning to launch in the country later in the autumn while Chadbourne & Parke is also reported to be considering an entry.

DLA Piper has expressed interest in launching a South America base for some time but is still in the process of deciding where to go.

Partners working in the region said the international law firms were being encouraged by Brazil's stable political climate as well as the opportunities stemming from its significant natural resources.

John Tucker (pictured), Americas managing partner at Linklaters, which is planning to grow its office in Sao Paulo, said: "Everybody has awaited the Brazil market to pick up and that time has come. There is now a much more active listed-company environment. The country has a stable political environment which favours this development."

Skadden corporate partner and Sao Paulo head Jonathan Bisgaier added: "Everybody seems pretty hot in the region. Brazil has a booming economy, same as China and India, and that means a lot of legal work."

However, Freshfields Bruckhaus Deringer still has no intention of joining the rush. Paris-based co-head of the firm's Latin America group, Nigel Blackaby, said: "You cannot serve all of Latin America from one office... our strategy has not changed and we continue to service Latin America from our existing offices."

Key Latin-American mandates in the last year

Brazilian mining company Vale's failed approach to Swiss rival Xstrata for an estimated $90bn (?49.4bn). Generated roles for firms including CC and Cleary Gottlieb Steen & Hamilton

Braskem's $4.5bn (?2.5bn) joint venture with Pequiven to create the largest petrochemical complex in Latin America and the largest polypropylene plant in the world has generated roles for firms including Linklaters

Glencore's discussions with the Bolivian Government for the renegotiation of its mining contracts and claim for expropriation of its Vinto tin smelter saw Freshfields acting