A huge cache of more than 11 million confidential documents has been leaked anonymously from Panamanian law firm Mossack Fonseca, apparently showing how the company how helped clients launder money, dodge sanctions and evade tax.

A wide network of offshore "shell" companies allowed the powerful and wealthy to hide their assets from taxes and, in some cases, to launder billions in cash over a number of years, it is alleged. The so-called "Panama Papers" cover a period from 1977 to the spring of 2016.

Mossack Fonseca insists, in a statement,  it has operated beyo...