John Shipton.

Julian Assange's father, John Shipton. Photo: Justin McManus

Julian Assange's father has engaged a silk to start legal action against Australian Prime Minister Tony Abbott and Foreign Minister Julie Bishop over comments relating to his political party's controversial visit to Syria.

John Shipton came under fire after the Australian WikiLeaks Party sent a delegation to Syria to meet accused war criminal, President Bashar al-Assad.

Mr Shipton is claiming that the comments made by Mr Abbott and Ms Bishop defamed him.

"Because of the defamatory statements made against myself by Prime Minister Tony Abbott and Foreign Minister Julie Bishop, we have asked barrister Clive A. Evatt to begin defamation proceedings seeking $5 million in damages in each case," he said.

One of Sydney's best-known defamation lawyers, Mr Evatt's clients have included Abe Saffron, Harry Seidler and 'Gypsy Fire' – performer Emilia Caruana who was wrongly portrayed by Truth newspaper as Bob Dylan's sex slave.

Mr Evatt said Mr Shipton had rung him from England on Thursday to engage his services.

"He's suing on defamatory comments made by Ms Bishop: They were all in The Australian a couple of days ago.

"She called him 'stupid and reckless', so he's suing on publicly being called stupid and reckless – that's Bishop.

"And Tony Abbott said more or less the same thing, reported in the media this morning."