Dentons and US-based law firm McKenna Long & Aldridge have agreed to combine, subject to approval by both partnerships, from January 1, 2014.

The majority of McKenna’s offices are in the US but it has one office located in Brussels which will serve as an expansion of Dentons’ existing office, and one in Seoul, which will be a new location for Dentons, that was opened this year.

Asia Pacific has become a more important market for Dentons in recent years with the company opening its Beijing, Hong Kong and Shanghai offices in 2011 and its Singapore office in 2009.

This will make Dentons will be the 10th-largest law firm in the US, where it will be known as Dentons US, and the fourth-largest law firm in the world, the company believes.

It will also create a regulatory powerhouse in sectors, including trade as well as insurance and a number of other fields. The Brussels office in particular will be focusing on international trade as well as arbitration, competition and European regulation advice.

If the combination is approved by both partnerships, Jeff Haidet, McKenna’s chair, will become CEO of Dentons US while Mike McNamara, managing partner of Dentons US, will become the managing partner of the merged Dentons US. Global chief executive Elliott Portnoy and global chair Joe Andrew will retain their positions.