The powerful and secretive organisation officially tasked with probing Australia’s spy agencies to make sure they stay within the law is about to get a new head, Prime Minister Tony Abbott has revealed.

The PM announced on Thursday that the present Inspector-General of Intelligence and Security (IGIS), Vivienne Thom, will be replaced in August by the Hon Margaret Stone who is now the government’s Independent Reviewer of Adverse Security Assessments and a former Federal Court Judge.

The role of the Office of the Inspector-General of Intelligence and Security (OIGIS) is one of the most highly sensitive in terms of security in the government because it retains the power to investigate intelligence agencies off its own bat as well as conducting regular annual audits to ensure that those running covert surveillance and collection activities stay between the lines.

It’s a dynamic and often unpredictable environment given recent issues that include accusations Australia bugged Timorese government facilities during resources negotiations, the death of Australian Israeli citizen Ben Zygier in jail in Israel and the Defence personnel security vetting scandal where whistle blowers revealed that outsourcers fudged background checks.

The IGIS’ extensive annual reports have also shown-up sometimes comical aspects of sypcraft gone awry, like the October 2014 revelation that the Australian Security Intelligence Organisation had accidently bugged itself.

“ASIO intercepted, without warrant, calls made from one of its own regional offices due to a technical error. The data was deleted and processes put in place to ensure it does not happen again,” the IGIS’ last annual report noted.

The Prime Minister used the announcement of a new head for the OIGIS to emphasise that “the Australian intelligence community operates within a robust oversight and accountability framework, and the Inspector-General plays an important role in reviewing the activities of the intelligence agencies.”

Mr Abbott said he intended to recommend to the Governor General, His Excellency General the Honourable Sir Peter Cosgrove AK MC, that Ms Stone be appointed as IGIS “for a period of five years from 24 August 2015.”

Mr Abbott also paid tribute to Dr Thom whose term as Inspector-General concludes on 18th July 2015, saying she had carried out her role “with diligence and integrity”.

The Prime Minister said that Jake Blight will act as the Inspector-General until 23 August 2015, when Ms Stone’s appointment commences.