Carol singers provide chorus of disapproval at Parliament

Singing "Silent Night" in public does not normally carry the risk of arrest but the peace activists gathered outside Westminster last night had been warned they could be breaking the law by staging a carol concert outside the Houses of Parliament.

But under the gaze of a giant statue of Winston Churchill, up to 150 took the risk and joined the seasonal celebrations in Parliament Square.

Had police chosen to define the gathering as a demonstration, the participants could have been detained and prosecuted under laws banning protests within one kilometre of Parliament. In fact, police kept a discreet distance as the activists, led by a solitary trumpeter, gave enthusiastic renditions of "O Come All Ye Faithful", "Jingle Bells" and "Amazing Grace". A minute's silence was held for "all those who have died and suffered as a result of conflict".

The hour-long event ended with the Lord's Prayer, led by Brian Haw, the veteran protester who has survived numerous official attempts to evict him from his "peace camp" opposite Parliament's gates over four years.

Maya Evans, 25, convicted for breaching Section 132 of the Serious Organised Crime Act after reading aloud the names of British soldiers killed in Iraq next to the Cenotaph on Whitehall, also joined the service. She said: "If we stand up to be counted and show we're not willing to allow government acts of legislation that infringe our civil liberties, we can make a difference."

The law, which came into force in April, was drawn up to prevent MPs from being disturbed by Mr Haw's loudhailer, which he has used daily to berate the Government over the war in Iraq.

Last night's event was organised by Tim Ireland, an Australian-born internet campaigner who uses an American-style web-log, www.bloggerheads.com, to campaign on issues from demands for an inquiry into the attacks on London on 7 July to the anti-terrorism laws.

He said: "The aim is to sing carols and that is it. The Serious Organised Crime Act outlaws demonstrations within the exclusion zone around Westminster but it does not define demonstrations. You could break it by wearing a Make Poverty History wristband or demonstrating your own stupidity."

Shami Chakrabarti, director of the human rights pressure group Liberty, said: "Welcome to the ghost of Christmas present in Britain - Singapore-style. Police are required to investigate carol singers and free speech is considered anti-social behaviour."