Suspended Essendon AFL coach James Hird claims he was never told he could refuse to disclose details to the joint AFL/ASADA doping investigation.

Hird says he was instead warned he could face AFL sanctions if he remained silent throughout an interview, which lasted nine hours and involved 1300 questions.

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In a writ filed with the Federal Court, Hird also claims ASADA breached a confidentiality agreement by delivering to the AFL a draft copy of its interim report in August last year.

Both Hird and Essendon are arguing last year’s joint ASADA and AFL investigation into the club’s 2012 supplements program was unlawful.

They claim the ASADA show-cause notices, detailing accusations of illegal drug use against 34 past and present players are therefore improper and should not proceed.

Hird has been studying in France following his 12-month suspension from the AFL but will return to Australia on July 28.

Hird and Essendon’s bid to derail ASADA’s investigation into the club’s supplements program will go to trial in August.

The case will return to court for a further directions hearing on Wednesday.