Members of the public should have the right to demand access to government data sets on everything from health to road traffic, the Conservatives party leader has said.

Civil servants should only be allowed to refuse requests for information if there is a risk to personal privacy or national security, according to proposals set out in a speech by David Cameron on Thursday.

He was setting out how a Tory government will attempt to shift the balance of power, limiting state powers of surveillence and increasing the state's accountability to the public.

On the basis that "information is power", he said, the Conservatives will identify "the most useful information in twenty different areas", such as the NHS, schools and road traffic, and publish it.

"This information will be published proactively and regularly - and in a standardised format so that it can be 'mashed up' and interacted with," Cameron promised.

"By harnessing the wisdom of the crowd, we can find out what information individuals think will be important in holding the state to account."

The government has already begun releasing data to individuals and community groups. An ongoing competition, Show Us a Better Way, offers financial support to the best idea for using government data, and world wide web inventor Sir Tim Berners-Lee was appointed this month to examine how to simplify and increase access to public data.

Cameron gave the examples of releasing crime data so that people could build their own crime maps, or standardising the publication of local authority meeting minutes so that a local version of TheyWorkForYou could be developed.

A cross-government list of jobs advertised and salaries offered could be compiled so that people could find out about vacancies and "make sure your money is being put to proper use", Cameron continued.

"Most of this information is kept locked up by the state," Cameron said. "And what is published is mostly released in formats that mean the information can't be searched or used with other applications, like online maps. This stands in the way of accountability."

His party, which has already announced plans to publish every item of government spending over £25,000, would create a "right to data" so that members of the public could request further datasets, he said.

"And to avoid bureaucrats blocking these requests, we will introduce a rule that any request will be successful unless it can be proved that it would lead to overwhelming costs or demonstrable personal privacy or national security concerns," he added.

The role of the Information Commissioner would be reviewed to ensure that it "is designed to maximise political accountability in our country", Cameron said.

Cameron also set out plans for limiting state powers, such as scrapping the identity card scheme and the database containing data on all children, Contact Point.

Innocent people would also be given the chance to remove their names from the DNA database, Cameron said in the speech at Imperial College in London.

He promised to review the use of the stop and search powers within the Terrorism Act of 2000 and change the controversial seven-year-old Regulation of Investigatory Powers Act.

Designed to catch serious criminals, the latter has controversely been used by councils to identify fly-tippers and, in one case, to make sure a family lived in a school catchment area.