China suspended an international anti-corruption task force after taking over the presidency of the Group of 20 earlier this year, according to six individuals in the group, who called it a setback to efforts to crack down on shell companies used to conceal assets.

The Anti-Corruption Taskforce of the G-20's Business 20 forum, comprising businesses and civil society groups, had been drawing up G-20 policies for increasing transparency of offshore financial structures, among other work, but the body was scrapped in late January because Chinese companies declined to participate, according to the sources.

China is one of several countries under pressure to share data about paper companies after the leaked Panama Papers documents from the Panamanian law firm Mossack Fonseca revealed how the rich and powerful use such structures to avoid taxes and in some cases conceal ill-gotten gains. They were published by the German newspaper Sueddeutsche Zeitung and more than 100 other international news outlets.