David Anderson QC to deliver findings after year-long examination of the extent to which communications should be monitored and the need for oversight

A key official report on overhauling Britain’s surveillance laws to be published on Thursday is expected to push for much stronger oversight of the activities of the police and security services.

The report by David Anderson QC, the official reviewer of the counter-terrorism laws, was commissioned by David Cameron in July 2014 as part of the debate over what should replace emergency surveillance legislation which is due to expire in 18 months’ time.

Anderson was asked to undertake “a comprehensive review of the capabilities our security and intelligence agencies need, and the safeguards that govern their access to private communications”.

The home secretary, Theresa May, has already promised that the government will respond to the recommendations of the Anderson report, which is believed to run to more than 300 pages, as she frames her investigatory powers bill over the summer. The new government legislation will include moves to enhance the interception powers of the security agencies as well as their “snooper’s charter” powers to track email, social media and phone use through communications data.

Anderson was asked to assess the current and future security threats to Britain, the capabilities needed to combat them, the privacy safeguards and oversight processes needed, the challenges of changing technology, and the case for new or amended legislation.

He has described it as a “substantial piece of work” and visited Berlin, California, Washington DC, Ottawa and Brussels as part of the review. “The report won’t please everybody (indeed it may not please anybody). But if it succeeds in informing the public and parliamentary debate on the future of the law, from an independent perspective, it will have done its job,” Anderson has written on his blog.

It is thought that the Anderson report is likely to clear the way for May to push ahead with the “snooper’s charter” powers but will insist it is done within a stronger oversight system and human rights framework.

The Anderson report comes after parliament’s intelligence and security committee recommended a new intelligence services act in the wake of the disclosures by the whistleblower, Edward Snowden. The MPs and peers said the new legislation should set out “clearly the intrusive powers available to the security agencies, the purposes for which they may use them, and the authorisation required before they may do so”.

A second secret report by Sir Nigel Sheinwald, the former British ambassador to the United States , commissioned at the same time as the Anderson report, is believed to have recommended that a new international treaty be negotiated to secure the co-operation of the giant American internet companies in providing their customers’ data in response to requests from British police and security services.

A report by the journalist Duncan Campbell in September of a Ditchley Foundation conference attended by senior intelligence figures suggested that post-Snowden a consensus had emerged in the intelligence community that a change towards transparency was both overdue and necessary.