A collaborative investigation, known as Mauritius Leaks, has allegedly revealed how an offshore law firm helped companies to drain tax revenue from African, Arab and Asian countries.

Over 200,000 documents from the Mauritius office of offshore law firm Conyers Dill & Pearman are the focus of the investigation. ICIJ corroborated company information from the leaked documents with data in the Mauritius corporate registry and the Financial Services Commission’s register of licensees.

The documents include emails, contracts and business plans provided by some of the world’s biggest players in finance and law, includi...