East Timor has instituted proceedings in the United Nation's top court in relation to ASIO raids on the office of a Canberra lawyer representing the tiny country.

The domestic spy organisation ASIO in early December raided lawyer Bernard Collaery's office and seized documents relating to a dispute with Australia over a $40 billion oil and gas treaty.

East Timor on Tuesday began proceedings in the International Court of Justice (ICJ) in The Hague over the seizure and detention of the documents which it says "belongs to Timor-Leste and/or which Timor-Leste has the right to protect under international law".

A statement issued by the court on Wednesday makes clear that East Timor wants the ICJ to declare that the ASIO seizure "violated the sovereignty of Timor-Leste and its property and other rights under international law and any relevant domestic law".

The documents relate to East Timor's challenge to the Treaty on Certain Maritime Arrangements in the Timor Sea (CMATS).