The Federal Court has thrown out a truth defence pleaded by the ABC and Fairfax Media in a defamation case brought by Chinese-Australian businessman Chau Chak Wing.

Mr Chau, one of Australia's most generous political donors, filed defamation proceedings in June last year against the national broadcaster, the newspaper group and Fairfax journalist Nick McKenzie over a joint investigation.

Chau Chak Wing leaves the Federal Court in June. Credit:Peter Rae

The ABC's Four Corners program and an accompanying online article painted Mr Chau as a spy who "betrayed his country" to serve the interests of the Chinese Communist Party, his barrister Bruce McClintock, SC, has told the court.

The stories also alleged Dr Chau funded a $200,000 bribe for a senior United Nations official, a claim the ABC and Fairfax Media claimed was true by drawing in part on a parliamentary speech given by federal Liberal MP Andrew Hastie in May.