Hibbert, an employee of Advanced Sports Nutrition and an associate of Stephen Dank, was originally scheduled to appear before ASADA on December 19. However, with the drugs probe threatening to drag on into next year, the man dubbed "The Gazelle" has welcomed the chance to tell his side of the story.

"In order to be co-operative, Darren has graciously offered to move forward his interview to assist ASADA in their aim to have the matter resolved before Christmas," Hibbert's lawyer, Zali Burrows, said. "The only reason he should be hauled before a government authority is to answer questions about his hairstyle."

In an intriguing twist to the inquiry, a witness who complied with an interview request - but challenged a notice to produce documents - was informed last week he could be liable for criminal prosecution.

The hardline stance is the first real test of ASADA's new powers, which include fines of $5100 a day for non-compliance. The maximum penalty for the obstruction of government officials carries a two-year jail term.

Ms Burrows, who represents that client, too, said it was a denial of natural justice.

"It is my client's intention to challenge the constitutional validity of the entire ASADA process, in particular the validity of the notices that are being issued," she said.

"This has happened all so very quickly before Christmas. If they are in a hurry to get this done, then why have they been dragging their feet for the best part of the year?

"We understand many athletes must be anxious to have this investigation finalised by the end of the year so they can enjoy Christmas with their family, yet my client complied with notice to attend an interview and was told the interview would not take place.

"We intend to challenge the notice to produce documents, not because he has anything to hide but because the participants are denied their basic human rights."