The Greens have called on the Federal Government to strip Wilson Security of its contracts for offshore immigration detention centres after revelations the company has links to a Hong Kong corruption scandal.

The call follows the unprecedented leak of more than 11 million documents from Panamanian Law Firm Mossack Fonseca, obtained by the International Consortium of Investigative Journalists and shared with media organisations around the world including the ABC's Four Corners program.

The leaked documents obtained by Four Corners showed that Thomas and Raymond Kwok, billionaire brothers charged with bribing a Hong Kong government official in July 2012, were in control of Wilson Security.

The brothers covertly remained directors of the offshore company that ultimately controls Wilson's operations in Australia — Wilson Offshore Group Holdings (BVI) Limited — following their arrests (Raymond Kwok was later acquitted of all charges).

In a statement to the ABC, Wilson insisted the Kwok brothers were never directors of Wilson Security.

But Greens Senator Sarah Hanson-Young described the revelations as alarming and said the Government needed to act immediately.

"Wilson Security must be stripped of their contract for running Manus Island and the Nauru detention centres," she said.

A spokesperson for the Department of Immigration and Border Protection said "the Commonwealth has strict rules for all procurement activities undertaken by Commonwealth entities".