Dentons is to merge with China’s largest firm Dacheng, to create the biggest law firm in the world by lawyer headcount.

The deal, which is understood to have been approved by partners at both firms but is awaiting sign off from Chinese regulators, will be the second merger between a PRC firm and foreign player following the union of King & Wood and Australia’s Mallesons Stephen Jaques in 2012, but the first of its kind for a firm with a significant US presence.