The government has been accused of creating laws that have a chilling effect on freedom of expression in the UK in a sharply critical report from the United Nations' committee on human rights. The report calls for the reform of Britain's libel laws and controls introduced under recent terrorism laws.

The government's use of the Official Secrets Act to prevent issues of public interest being published is also condemned in an intervention from the UN which warns that public servants are being gagged even where national security is not at risk.

The criticisms are made as part of the committee's analysis of a report which the UK is required to submit to the UN every three years, appraising human rights in its jurisdiction.

Among the problems identified, the UN says:

· Terrorism Act 2006 provisions covering encouragement of terrorism are too broad and vague, and should be amended so that their application does not lead to "a disproportionate interference with freedom of expression".

· Libel laws should be reformed to end so-called "libel tourism", whereby wealthy foreigners have gone to the high court to sue over articles that would not warrant action in their own country.

· Powers under the Official Secrets Act have been "exercised to frustrate former employees of the crown from bringing into the public domain issues of genuine public interest, and can be exercised to prevent the media from publishing such matters".

The committee also warns that, in the age of the internet, Britain's unduly restrictive libel laws create the danger of affecting freedom of expression worldwide, contrary to a UN covenant on civil and political rights which guarantees the right to freedom of speech and to exchange ideas and information "regardless of borders".

On the phenomenon of libel tourism, the case which has provoked most concern is that of the American researcher Dr Rachel Ehrenfeld, who was sued in London by a Saudi businessman and his two sons over a book which was not published in the UK, although 23 copies had been sold here via the internet and one chapter was available online. The action led to the New York state legislature passing legislation to protect writers and publishers working there from defamation judgments elsewhere, unless the defendants enjoyed the same freedom of speech rights as under New York and US federal law.

The UK government has been urged to consider "a so-called 'public figure' exception", which would require a would-be claimant to prove actual malice by a publisher or author. This would apply in cases involving public officials and prominent public figures, as currently exists in the US, where a public figure can only sue for libel if he or she can demonstrate malice, recklessness or indifference to the truth.

The 2006 Terrorism Act's "broad and vague" definition of the offence of "encouragement of terrorism" - an offence which can attract a jail term of seven years - was also criticised by the committee.

"In particular, a person can commit the offence even when he or she did not intend members of the public to be directly or indirectly encouraged by his or her statement to commit acts of terrorism, but where his or her statement was understood by some members of the public as encouragement to commit such acts," concluded the committee.

The government's abolition earlier this year of the common-law offences of blasphemy and blasphemous libel in England and Wales was noted and welcomed, as was the adoption of the civil partnership act recognising unions between gay and lesbian couples.

The UK also came under fire for its treatment of the Chagos Islanders, whose case for return to their former homes was heard by the law lords last month. The committee urged that the islanders be allowed to return, and also be compensated.

There was also condemnation over the extension of detention without charge from 14 to 28 days under the Terrorism Act. The committee was "even more disturbed" at plans to extend this to 42 days.

On the issue of the libel laws, media law specialist Mark Stephens said yesterday that "libel lawyers in this country have remained insouciant to the deficiencies highlighted by the UN" .

The civil rights organisation, Liberty, has already expressed concern about the Terrorism Act and its potential effect on free expression. "Free speech has been a victim of the 'war on terror', with offences of 'encouragement' and 'glorification' of terrorism threatening to make careless talk a crime," said a spokesperson.