Fast-growing U.K. firm Osborne Clarke (OC) has formed a best friend relationship with Indian start-up BTG Legal, founded by Prashant Mara, the former co-head of its India Group.

The two firms have already jointly handled matters for Facebook Inc, First Solar Inc, TRUMPF, Aveva, Investec and Cartelis.

This is the second firm that OC has established a relationship with in Asia after its strategic alliance with John Koh & Co in Hong Kong, and this marks the second phase of OC's investment beyond Europe and the U.S. The firm has grown from six to 19 offices worldwide over the past three years with a headcount of 600 lawyers.

Mara, who worked at Osborne Clarke in Cologne and London from 2009 until February 2014, founded the Mumbai-based BTG earlier this year. Before his stint with OC, he was with French law firm Franklin in Paris for two years, prior to which he worked with Indian firm J. Sagar Associates and Indian information technology company Infosys Ltd.