Government proposals to share information between departments have been criticised by the Information Commissioner's Office (ICO) as "too wide".
The data protection watchdog has also called for current provisions for the ICO's power to be extended to be further broadened.
The ICO has made a number of criticisms in an updated commentary on the Coroners and Justice Bill - a controversial plan that aims to provide stronger inspection powers for the ICO and to remove barriers to Whitehall data sharing to support improved public services.
Measures to improve its powers to spot-check government departments should be extended to the private sector, the watchdog notes.
"The risks can be just as great outside the public sector and the boundary lines between the sectors are increasingly blurred," says its commentary. Such an extension of the Commissioner's powers was also backed by a recent House of Lords report on the surveillance society.
And current conditions for obtaining a warrant for entry are not strong enough, the ICO warned.
"The Commissioner should have the power to intervene where there is a significant risk, and not only once a breach has taken place," says the commentary.
The watchdog is also concerned that the current Bill provides no sanction for data controllers that fail to comply with an assessment notice.
And measures to improve information sharing in the public sector are too wide ranging, according to the ICO notes.
"[Information sharing] provisions should only apply in precisely defined circumstances where there is a legal barrier to information sharing that would be in the public interest," it says.
The Bill also has a loose definitions of "personal data" and "information sharing" which need to be clarified in order for its provisions to dovetail clearly with the Data Protection Act.
After HM Revenue and Customs lost the personal details of 25 million families in 2007, prime minister Gordon Brown said: "We will give the Information Commissioner the power to spot check departments, to do everything in his power and our power to secure the protection of data."
The British Computer Society and the British Medical Association have also criticised the Bill and warned that the sweeping data sharing proposals go too far.