More than half of the current requests made to the archives for documents held by the archives are still waiting to be processed more than 90 days after the request was made, falling outside the period in which the Archives is meant to provide documents or explain why access hasn't been granted.

Access to ASIO documents more than 20 years old can be made through the National Archives, who then make the decision regarding access in consultation with the spy agency.

According to newly released data, out of 420 open applications for documents, some 30 per cent of applications have been waiting for more than four years.

More than half the open applications have been open for longer than a year, and the longest open application has been waiting for 11 years and five months.

A spokeswoman for ASIO defended that time, saying the agency was waiting for follow-up action from the applicant, and they heard back, other requests were being prioritised.

"ASIO has answered many hundreds of requests from this applicant," the statement said.

A spokeswoman for the National Archives didn't say if it took action to hasten the time ASIO took to approve access to documents, but said the arrangement between the two agencies acknowledged the 90-day period for an access decision.

"As is the case with other agencies, the National Archives regularly engages with ASIO to secure advice on records subject to applications for access," the spokeswoman said.

The Archives spokeswoman didn't say if more powers were needed to increase cooperation from agencies that control access to documents.

The open access period for documents was changed from 30 to 20 years old in 2011, with the transition increasing the number of documents that can be requested, and the complexity of assessing the security implications of releasing documents is growing.

A spokeswoman for ASIO said it has two tracks of requests - fast track, or bulk access, with fast track often relating to family queries and bulk access relating to a broad range of material. She also said the prioritisation of requests was informed by several factors.

"A single request could be as simple as determining that no record exists, or as complex as assessing multiple volumes that could encompass tens of thousands of pages," the spokeswoman said.

"ASIO works closely with the National Archives of Australia to facilitate the release of archival records in response to requests, while balancing various and often competing priorities."

"Prior to public release, ASIO undertakes a rigorous assessment to ensure the release of historical records while exempting information or matters which could reasonably be expected to cause damage to the security, defence or international relations of the Commonwealth."

Centre Alliance Senator Rex Patrick, who requested the figures from the Archives, said the delays were a disgrace.

"ASIO and the National Archives are clearly not taking their statutory obligations seriously. ASIO is exempt from Freedom of Information legislation and access to ASIO files is only available through the Archives Act, yet even this very limited direct public scrutiny of their activities appears too much for them."