Councils and other public bodies face a stiff test to comply with new website cookie legislation, according to public sector IT managers' association Socitm.
An audit for Socitm of 603 public sector websites, covering all local authorities and 170 other public sector organisations, has shown that all but six of them have cookies.
On average each site has 32 cookies, with the largest number found on a single site being 1,346. Many sites, said Socitm, have cookies set by third party system suppliers and websites such as Twitter and Google made available through the website.
Martin Greenwood, programme director for Socitm Insight, said: "We have compared the number of cookies found by our audit with those declared by some of the organisations that have already taken action on cookies. It is difficult to check for cookies and in every case we have found significantly more cookies than the site owners are aware of."
The cookie legislation came into force this May after a European directive was adopted by the UK government. All websites must allow visitors to be able to stop cookies being installed on their own machines, if they so wish on privacy grounds.
The government and UK information commissioner have said they will hold back for a year from taking action against those sites that do not comply immediately - providing they can prove they are taking action now to eventually meet the legislation.
Socitm recently launched its Cookie Management Service to help public bodies comply.