Campaigners will mount a legal challenge in the House of Lords today, as they attempt to limit the laws giving police sweeping powers to stop people even if they have no grounds to suspect them of a crime.

The Home Office revealed that people were being stopped at the rate of nearly 100 a day under the powers used to detain a peace campaigner, Walter Wolfgang, at last year's Labour Party conference.

Figures in a Home Office report showed that 35,776 searches of vehicles and people were recorded under Section 44 of the Terrorism Act, which was passed six years ago. Despite the high number of people stopped, only 455 were arrested. The newest statistics, which cover the 2004-05 financial year and do not include the aftermath of the July bomb attacks on London, represent a record use of the powers since the Act came into force.

The Home Office insisted the powers were essential to disrupt terrorist activity.

But campaigners warned that the law opened the door to discrimination and could be used to suppress legitimate demonstrations. A detailed breakdown of people stopped under the Act in 2003-04 found that more than one in five of those stopped were black or Asian, while reports suggest a huge increase in the number of black and Asian people being stopped since the London bomb attacks.

Lawyers acting for the civil rights pressure group Liberty will launch a test case in the House of Lords today, claiming the law breaches fundamental human rights.

They will press the case of Pennie Quinton and Kevin Gillan, who were among about 140 people arrested under the Terrorism Act at an international arms fair in east London in 2003.

Ministers also face opposition in the House of Lords next week when Liberal Democrat and Conservative peers will attempt to tighten the law to limit the power of police to authorise blanket stop-and-search operations.

Under conventional law, you can be stopped and searched by police if they have any suspicion you have committed a crime.

But the Terrorism Act, when sanctioned by a senior officer, allows police to stop and search people even without suspicion - something that campaigners say is a throwback to the notorious "sus" laws of the 1970s. Shami Chakrabarti, the director of Liberty, said: "This is almost worse than the sus laws. The police have the power to change the law of the land in whole parts of the country.''

Dominic Grieve, the shadow Attorney General, said: "These figures speak for themselves. The powers are being used as a blunt instrument and it is far from clear if those arrested are being done so for terrorism. "While we accept such powers may be necessary to protect the public from terrorism, it is vital these powers are not abused."
A spokeswoman for the Home Office insisted the legislation was needed to disrupt potential terrorist attacks. She said: "Stop and search under Section 44 is an important tool in the fight against terrorism. As part of a structured strategy, it aims to create a hostile environment for would-be terrorists to operate in."

John Catt, retired builder: 'It is very menacing when this happens'

John Catt, 81, an anti-war campaigner, has been stopped twice under the Terrorism Act. On the first occasion, the retired builder was stopped in east London and police searched the van he was driving. He said: "I was stopped in Shoreditch when I was pinned in by two police cars. They asked ridiculous questions like where was I going and why, how old I was and where I had been. They searched the back of the van and gave me a receipt to say why I had been stopped."

On the second occasion, he was questioned as he walked through Brighton wearing an anti-Blair T-shirt. He had been making his way to an anti-war demonstration at the seafront, outside the Labour Party conference in the city.

He said: "I was walking down Middle Street in Brighton towards a protest against the war and so on. I had a T-shirt on and had a plastic bag with some felt pens and some board because I draw." He said he was stopped and asked questions, before continuing to the demonstration. He said: "It is very menacing when you see this happening. Our civilisation is on the line."

Kevin Gillan, Student: 'They went through all my stuff'

The police stopped and searched Kevin Gillan as he cycled to an arms trade demonstration in London three years ago. He will challenge the Terrorism Act in the House of Lords today, claiming that it is a breach of human rights. His case, and that of the photographer Pennie Quinton, is backed by the civil liberties pressure group Liberty.

Mr Gillan, 28, a PhD student from Sheffield who has been researching political protests, was among 140 people arrested under the Terrorism Act outside an international arms fair in 2003 in London's Docklands.

Mr Gillan said: "I was within sight of the Excel Centre when the police stopped me. They asked to search me and said it was under the Terrorism Act. A police officer went through my stuff and confiscated some bits of paper with details of other demonstrations. It took about 20 minutes.

"I was pretty amazed that they were using anti-terror legislation against protesters. The law is giving an incredible amount of power to the police. It is an exceptionally strong law. These are supposed to be extraordinary powers, not used all the time."