Seeking nullification of its 2006 treaty with Australia dividing undersea oil and gas reserves, East Timor has approached the Permanent Court of Arbitration in The Hague, Netherlands. Proceedings began Thursday, to set up the procedural guidelines for the dispute arbitration, which experts believe could last almost a year.

Reports say, representatives from East Timor and Australia spent seven hours locked in private talks at the Permanent Court of Arbitration, which the East Timorese Ambassador to London, Joaquim da Fonseca, termed as very productive.

"We had a very productive proceeding today, unfortunately we had to do this against the background of the events of the past 48 hours," Mr da Fonseca said.

He was referring to the Tuesday raid on home/office of lawyer Bernard Collaery, who is acting for East Timor in The Hague, and a former Australian Security Intelligence Service (ASIS) spy who is the key witness in the case. The former ASIS spy was detained for some hours, and his passport cancelled, making it impossible for him to travel to The Hague to give verbal evidence.

The East Timorese Prime Minister has demanded explanation from his Australian counterpart Tony Abbott on the spying charges.

Following Tuesday's raid, which was criticised by Australia's opposition and East Timor, Attorney General George Brandis said he had authorised it in response to a request from the Australian Security Intelligence Organisation (ASIO) director-general David Irvine, who said the key witness and whistleblower in the case is a former senior spy who oversaw the bugging operation. Mr Brandis alleged that the former spy broke the law by revealing classified information.

Under a sworn affidavit, the former spy, who was then director of technical operations at ASIS, said he was asked to plant microphones in the Timorese cabinet room (which was constructed and renovated with Australian aid), in 2004. This was during the period when the deal was being negotiated, by the then-head of ASIS David Irvine.

Interestingly, Mr Irvine now heads the ASIO which carried out the Tuesday raid.

The whistleblower spy said he was concerned that the bugging was used by the Australian Government for commercial purposes and not in the interest of national security.

Following the revelation, East Timor, arguing that Australia broke international law, is seeking nullification of the CMATS ('certain maritime arrangements in the Timor Sea'), which it entered into with Australia in 2006.

The treaty provisions the 50:50 division of the billions of dollars revenue from the exploration of undersea oil and gas reserves in the Greater Sunrise field, over which both nations are claiming sovereign right.

East Timor argues that Australia bullied it to share income from the undersea resources, estimated to be $40-50 billion worth of oil and gas, which it rightfully owns.

Notably, the disputed oil and gas field lies 150 km south of East Timor and 450 km north-west of Darwin, Australia.

The treaty was signed by Australia's then-Foreign Minister Alexander Downer and his East Timorese counterpart Jose Ramos-Horta and came into effect in 2007.

Given the lingering dispute, Woodside, the Australian company which owns a third of the rights to develop the oil and gas fields, has not yet started production.

Interestingly, Mr Downer, the then Australian foreign minister who signed the CMATS treaty, left politics in 2007 (the year the treaty came into effect) and started a consulting firm which lists Woodside as one of its clients.