Beijing-based law firm Dacheng Law Offices on Tuesday merged with global law firm Dentons in a deal that will create the world's largest law firm by attorney numbers.

The merger will substantially boost the client base for both firms, with the new entity having more than 6,500 lawyers in 120 offices in more than 50 countries and regions.

The alliance will extend Dacheng's reach in foreign markets at a time when companies from the Chinese mainland are increasingly engaged in international mergers and acquisitions.

Dentons will benefit from Dacheng's network in China, which it had little access to before the merger.

The new firm will go through a three-year transitional period during which it will sort out issues including profit-sharing and potential client conflicts, according to partners at Dacheng.

With the deal, Dacheng becomes the first Chinese law firm to form an alliance with a foreign law firm with a global presence.

Five partners from Dacheng will be included in the new firm's 19-person global board of directors. Peng Xuefeng, the founding partner of Dacheng, will be the chairman of the board. Joseph Andrew will continue to act as the new firm's global chairman while Elliot Portnoy will be the global chief executive.

The merger was carried out under a structure known as Swiss verein, which combines different firms through sharing their strategy, branding and other core functions while keeping their accounting and partner compensation structures separate.

Peng said that the alliance will allow Dacheng to help its Chinese clients in their overseas deals and provide them with legal services that transcend geographic and cultural barriers.

It will also allow Dacheng to catch up with its Western counterparts in terms of legal professional standards and globalization, he said in Beijing on Tuesday.

Portnoy, global chief executive of Dentons, said: "It has been clear that our clients regard China as the most important market for their business."