A lawyer representing East Timor has foreshadowed possible legal action against ASIO boss David Irvine over his involvement in the alleged 2004 bugging of Dili’s cabinet office.

Bernard Collaery is part of the East Timorese legal team challenging a $40 billion oil and gas treaty with Australia on the grounds that Canberra engaged in espionage during negotiations to gain an unfair advantage.

An unnamed former technical operations director at the overseas spy agency ASIS has reportedly given an affidavit stating that in 2004 Mr Irvine – then ASIS’s director-general – ordered him to plant listening devices.

“Clearly the current director of ASIO who directed the unlawful break-in to the East Timor cabinet office should be answerable to the law,” Mr Collaery told AAP.

“I am determined to have Mr Irvine answer for his actions.

“It is time the federal police and the Commonwealth Director of Public Prosecutions examines the events that led to the unlawful activities in 2004.”

Mr Collaery was speaking in the Netherlands where earlier in the day he represented East Timor in its dispute with Australia at the Permanent Court of Arbitration.

This week ASIO raided Mr Collaery’s Canberra office and seized documents relating to the case.

The domestic spy agency also detained the former ASIS officer and cancelled his passport.

But Mr Collaery on Thursday insisted the former officer, now East Timor’s prime witness, was given approval by the then inspector general of security to take his concerns over the 2004 bugging operation to a lawyer.

Mr Collaery was also highly critical of the seizure of East Timor legal opinion by international law experts Sir Elihu Lauterpacht and Professor Vaughan Lowe along with his own correspondence with Prime Minister Xanana Gusmao.

“(It) illustrates to the world that Australia will break every convention and any rule of law to protect the unlawful activity undertaken in 2004 in respect of the gas revenues in the Timor Sea,” he said.

Attorney-General George Brandis on Thursday said the oil and gas treaty that East Timor is challenging required “prior consultation” before a party could seek arbitration in The Hague.

He argued East Timor had not “sufficiently engaged in or exhausted the prior consultation machinery”.

But Mr Collaery said he wasn’t aware of Senator Brandis’s argument.

He added any suggestion that East Timor didn’t consult and offer Australia a confidential settlement was “arrant, misinformed nonsense”.

“It was former foreign minister Bob Carr and then attorney-general Mark Dreyfus who disclosed Timor-Leste’s case in a May 2013 media interview,” the lawyer said.

Mr Collaery is a former ACT attorney-general.