LONDON — BRITAIN is about to make a decisive break with several centuries of sympathetic treatment of people arriving at ports of entry, asking to be treated as refugees.The government is moving to replace its long-standing open-door policy toward asylum-seekers with a new law which will include finger-printing of asylum- seekers and institute a fast-track system for sending back people whom the authorities deem economic refugees. The Asylum Bill means that the country which welcomed the French Huguenots in the 16th century, gave political shelter to such figures as the 19th century Russian revolutionary Alexander Hertzen, and accepted thousands of Jews fleeing Nazi Germany is replacing generosity with skepticism about the claims of new arrivals. Despite pleas from leading churchmen, lawyers, and politicians that the Asylum Bill is unfair and may worsen race relations, the tough new measures are expected to receive royal assent by the end of the year. The legislation, designed to curb asylum applications currently running at the rate of 1,000 a week, was denounced on Nov. 13 by the Archbishop of Canterbury, George Carey, and Cardinal Basil Hume, leader of England's Roman Catholics, in a joint letter to The Times of London. Home Secretary Kenneth Baker flatly rejected their call to rethink the legislation. A similar plea by the British Bar Council was also turned down. Hours later, the controversial bill passed by a 78-vote majority in the House of Commons. Mr. Baker and other government ministers defend the new measure by pointing to a Europe-wide upsurge in the movement of people seeking refugee status. "Other countries, including France, Switzerland, and the Netherlands, face the same problem and are taking similar measures," Baker said in a House of Commons debate Nov. 13. The numbers of people arriving at London's Heathrow airport and other entry points confirm that the trend is rising sharply. More than 50,000 applications were made in the last 12 months - 10 times the number in 1988. "It would be grossly irresponsible for the government to ignore the trend," Baker argued. "We must strengthen our defences." But the government's methods of dealing with the problem have drawn rebukes from a wide range of causes concerned with the welfare of refugees. Frank Krenz, London representative of the United Nations High Commissioner for Refugees, called the new rules "biased against the applicant." Alf Dubs, director of the British Refugee Council, accused the government of setting up barricades against refugees which, he maintains, contravene the 1951 UN convention on refugees. Roy Hattersley, deputy leader of the opposition Labour Party, denounced the bill as racist. Mr. Hattersley accused the government of "an obsession with reducing the numbers of refugees" and predicted the new rules would result in genuine asylum-seekers being "sent back to imprisonment, torture, and death." Under the 1951 UN convention, the government is obliged to admit all those with a "well-founded fear of persecution." The new legislation proposes to speed up decisions on whether an asylum-seeker's fears are well-founded. It lays down stringent rules for the guidance of immigration officers, whose numbers will be increased. As well as being finger-printed, applicants will have to get their legal advice from a government-funded body. They will not be able to obtain government financial aid to pay for counsel of their choice, as they can now. Applicants must immediately make a full disclosure of the facts of their case and produce some kind of travel document. If they claim to have been persecuted in their own country, they must prove that before coming to Britain they sought refuge in a safer part of their homeland or in a neighboring state. The government hopes that most undeserving asylum-seekers will have their cases heard and rejected within 72 hours. No case will take longer than 90 days to process. Under present rules it can take up to two years for cases to be decided, and there is a backlog of 60,000 applications. The new process contrasts sharply with established practice, and large numbers of asylum-seekers will likely be sent back. According to the Home Office, about one quarter of recent asylum-seekers have been granted full refugee status. Another 65 percent were granted "exceptional leave to remain" for 12 months on humanitarian grounds. Government and opposition spokesmen agree the latter category will be heavily reduced under the new rules. William Wallace, an international affairs specialist at St. Antony's College, Oxford, said the problem of a rapid increase in applications for asylum was Europe-wide. In Britain's case a long liberal tradition of accepting refugees had been placed under acute strain, he said. "A single refugee is a heroic figure, welcome to asylum," Dr. Wallace wrote in the Guardian daily Nov. 2. "A thousand are a problem. A million are a threat."