A LETTER from a young man published in the Guardian on Thursday warned the Labour Party that if it wins the next general election, it could be faced with "jailing hundreds, maybe thousands, of citizens, for resisting the exercise of arbitrary power. Tensions between the police and public will rise to dangerous levels. The potential for civil commotion and riot will be great".

The letter appeared the day after the British government rushed through emergency legislation to extend the powers of the police under the Prevention of Terrorism Act.

The warning in the letter bears some comparison with the conclusion of an unofficial inquiry conducted by the Labour peer, Lord Gifford QC, into the role of the Metropolitan Police in the run up to the Broadwater Farm estate riots in the Tottenham area of London in 1985.

He found that "accumulated bitterness" between the police and residents on the estate, the restrictions on the free movement of local people and "years of discriminatory practices by the police", combined with criminal activity on the estate, created an atmosphere of deep seated distrust on both sides.

While present Labour MPs are not suggesting that the extension of police powers will lead to another "Broadwater Farm", the suspicion of some of the Labour MPs who voted against them is that they represent, in a diluted form, the "stop and search" measures which became well known in Britain in the 1970s.

One Labour MP, Ms Diane Abbott, who believes the new law will damage police and community relations, says she voted against the legislation because "the police don't need more powers".

The concern of ethnic communities in Britain, she says, is that if a young, black male is already five times more likely to be stopped by the police than any other youth, this legislation will "embitter police and community relations in a repeat of the situation in Northern Ireland".

The former shadow Northern Ireland secretary, Mr Kevin McNamara, says the legislation will "alienate whole generations. Many more black and Asian people will be stopped and the negative aspect will far outweigh the positive gains".

The expansion of police powers under the PTA will mean that anyone walking the streets of Britain can be stopped by a police officer and asked to remove their outer clothing or shoes or hand over anything they are carrying to be searched. The new law requires the public to do this if a police officer believes the articles could be used in connection with "the commission, preparation or instigation of acts of terrorism".

The PTA's power does not stop there. It also allows the police to create "designated areas" of any size, for up to 28 days, within which the police have powers of entry, search and seizure of material "expedient . . . in connection with an act of terrorism".

It is not simply a case, however, of a street in London being cordoned off if the police suspect a bomb may have been planted in a building or a train station. The reality is that a pub, a lock up garage or even someone's home could become a "designated area". Everyone on that street or in that pub can be searched and questioned under the PTA. Anyone who does not co operate can be imprisoned for a maximum of six months.

The British Home Secretary, Mr Michael Howard, believes that even if the new powers do not prevent all terrorist attacks, they may succeed in permitting the early detection of some. He feels they may also enable the police to remove some drugs, weapons or obscene material from circulation.

But as a deterrent, many people will question the effectiveness of the laws since such a small number of people have ever been charged with terrorist activity in Britain under the PTA. From over 7,000 people detained, fewer than 10 have been charged with terrorist activity.

"It is all about approach," says Father Jerry Kivlehan, director the London Irish Centre in Camden. "The effectiveness of the legislation depends on the way it is implemented by the police. But we feel that this legislation is primarily targeted at the Irish community who are only too aware of the harassment they have been subjected to by the police when they have been stopped at airports and in the street.

"Everyone understands the need for counter terrorism measures, but there could be problems if someone who doesn't know they are walking about in a `designated area' is questioned by the police, perhaps in an aggressive way, and this could be counter productive."

If it is still too early to say if the new law is anti Irish in practice, Liberty, the National Council for Civil Liberty, is deeply uneasy at what it calls a "knee jerk measure" designed by the government to "exploit the public's concern" over recent IRA activity. Liberty is concerned that it will add to the problems between other ethnic groups and the police.

The director of Liberty, Mr John Wadham, says that since the introduction of the "ring of steel" in London, a disproportionate number of black people have been stopped and searched despite the fact that no black people have been involved in IRA activities in Britain.

"Without a Bill of Rights, it is appallingly easy to rush through such ill thought out legislation . . . A great number of people will be stopped and searched when their only `crime' is to be Irish."