Seventy-six organisations have written to the prime minister urging him to drop proposals to restrict the freedom of information (FoI) act.

Various campaign groups, charities and press bodies have signed the letter to David Cameron, arguing against the watering down of the act.

They say the proposals are not compatible with Cameron's stated aim of making Britain "the most open and transparent government in the world".

The sending of the letter has been timed to coincide with an international summit on open government, hosted by the British government in London tomorrow.

The event will be attended by representatives from more than 60 countries. Each government - including the UK - is expected to announce new commitments towards greater openness, drawn up in partnership with non-governmental organisations from their own countries.

It was in November last year that the government announced that it was considering a series of proposals to make it easier for public authorities to refuse FoI requests on cost grounds. Those proposals are still under consideration.

The government says the changes are intended to address the "disproportionate burdens" caused by those people or bodies who are said who make "industrial use" of the FoI act.

But the 76 organisations say "the proposals would restrict access by all users, including those making occasional requests of modest scope."

FoI requests can already be refused if the cost of finding the requested information exceeds certain limits. The government says it is considering reducing these limits, which would lead to many more requests being refused.

It is also proposing to allow more activities to be taken into account when calculating whether the limit has been reached.

Instead of only counting the cost of finding and extracting the information it also wants to include the cost of considering whether or not to release it. Other restrictions are also being considered.

The organisations argue that "many requests of substantial public interest would be refused under these proposals regardless of the benefits of disclosure. They would have a severe effect on the operation of the FoI act."

Their letter concludes: "We find it difficult to reconcile the commitment to become the world leader in openness with the government's proposals to restrict the FoI act, which is a critical element of the UK's openness arrangements.

"Many requests of substantial public interest would be refused under these proposals regardless of the benefits of disclosure. We hope that the government will mark that commitment by announcing that it will not be bringing forward proposals to restrict the act."

A more detailed list of concerns was sent to the government in May this year by the Campaign for Freedom of Information.

That organisation has organised the drawing up and sending of the letter. Among its 76 signatories are the Society of Editors, the Newspaper Society, the National Union of Journalists, Guardian News & Media, the London Evening Standard, the Independent and Independent on Sunday, the Daily Mail and the FoI campaigner Heather Brooke.

Source: Campaign for Freedom of Information