An ex-spy known as "Witness K" has indicated he will plead guilty to breaching the Intelligence Services Act, but his lawyer Bernard Collaery will continue to fight the charge in a case that was today committed to trial in the ACT Supreme Court.

Both men were charged last year with conspiring to reveal secret information, relating to allegations Australian Government agents bugged the cabinet room of East Timor during sensitive negotiations between the countries on oil and gas.

Witness K and Mr Collaery were each charged with a single count of conspiring to share information protected by Section 39 of the Intelligence Services Act, which covers secrecy and the unauthorised communication of information.

Today, in court, lawyers for Witness K, a former Australian Secret Intelligence Service spy, said the charges related to communications with the East Timorese government.

They told the court their client would plead guilty.

But his lawyer, former ACT attorney-general Bernard Collaery, will fight the conspiracy charge against him in the ACT Supreme Court.

The dramatic developments have headed off a closed hearing that was to run this week where issues of national security likely to be included in the case were to be discussed.

Much of the case so far has been shrouded in secrecy, and it is illegal to reveal details of the spying operation or reveal Witness K's identity.

The cases of Witness K and Mr Collaery were first heard in open court a year ago, and have been slowly progressing through the justice system since.

Witness K's plea of guilty and Mr Collaery's subsequent committal to trial marked the first divergence of the two cases, but outside court Mr Collaery said he understood the position his former client was in.

"I have great empathy for Witness K and the struggle that Witness K has gone through spiritually, mentally and physically," he said.

"I can understand the position, after six long years, Witness K has found."

Protesters outside the ACT Magistrates Court last year, when the case first began. ( ABC News: Ian Cutmore )

Mr Collaery said he was grateful for a small group of supporters who protested outside the court.

"It warms my spirit to see that Australians are becoming concerned about the state of our democracy, the freedom of expressions, the restrictions on the media and that I would be put to my trial for giving legal advice, in good faith, to a member of the security services," he said.

"This is a very determined push to hide dirty political linen, that's what this is all about, dirty political linen under the guise now of national security imperatives."

Case will return to court later in August

Mr Collaery said he was felt capable of fighting the charge against him, saying "I'm from Wollongong. I grew up playing in the mud and there's going to be a lot thrown back soon."

But he stopped short of answering questions, expressing concern for the journalists who were present outside the court.

"I'm sorry but for the first time in my career, I will not answer questions. It might bring you into trouble," he said.

"I'm very conscious that I need to keep my powder dry, to deal with this contemptable charge against me."

Instead Mr Collaery issued a statement with further information, including that he planned to defend his profession, the legal advice he provided and the rights of the journalists named in the charges against him.

"It is with a heavy heart that I shall enter the dock of the courtroom where I have spent my entire career supporting the Rule of Law. Those principles hold that Ministers are as bound as any ordinary citizen to maintaining ethical and legal codes of behaviour. You might forgive me for thinking, after more than 40 years in the law, that I might understand injustice. Clearly I have more to learn. I can say no more because I am silenced by a law we gave our political leaders to fight terrorism."

Lawyers for Witness K said they only finalised his agreement to plead guilty this morning, but were still negotiating with the prosecution over the full details of the case.

Both cases will be back in court later this month.