After an emotional debate that provided a rare national forum for the racial fears of many white Britons, delegates at the Conservative Party's annual convention today strongly urged their government to move immediately to strengthen already stringent restrictions on nonwhite immigration.

As a large number of the delegates filling the ornate Winter Garden convention hall here strongly applauded, speaker after speaker told government officials that in the words of Basildon city councilman Victor York, "We must stop immigration now."

Plymouth constituency chairman Robert Brown presented a resolution that he said reflects "the innermost and often spoken views of the party's grassroot and the country as a whole." It says the government "should recognize that Britain is a small and overcrowned island and great care is needed to ensure that the future identity of the nation is not overwhelmed by outside influences and that houses, hospitals and jobs are readily available to our own people suffering additional demands from immigrants."

Britain has strict immigration regulations that make it difficult for additional people from nonwhite Commonwealth nations in the Caribbean, Africa and Asia, including relatives of those already settled here, to come here to live.

The Conservative government of Prime Minister Margaret Thatcher is considering further restrictions to keep out most of the 10,000 to 20,000 spouses, children and parents of nonwhite residents still admitted each year. It also is writing a new definition of British nationality that may prevent many nonwhite immigrants who have lived and worked here for 10 to 20 years from becoming full British citizens.

But the government has not been moving fast enough to satisfy the many convention delegates who strongly supported Brown's resolution in a version eventually toned down somewhat.

The vast majority of people allowed to settle in Britain each year actually are whites who fall into three categories and who have an unrestricted right to enter and stay here. They are Irish citizens, nationals of Common Market countries who take jobs here and the mostly white residents of Commonwealth countries whose parents or grandparents were born here.

The government is not planning any restrictions affecting them and it was clear that today's debate was not about them. Rather it was about the several million blacks and Asians who settled here in the 1950s and 1960s, the vast majority recruited by British employers for construction, transportation and other jobs then unfilled.

Delegates accused the immigrants of swelling relief rolls, aggravating job and housing shortages and transforming a once homogeneous culture.

Home Office Minister Timothy Raison, who has the responsibility for proposing changes in immigration laws, told the delegates, "We know that many of our fellow Britons now are black and brown, and that nothing will alter that fact, whatever our immigration rules. We know that they, like all of us, have their sensitivities as well as their customs and religions."

He said the government must provide the "opportunity for our brown and black citizens to get on and make the best of what they have to offer, as more and more of them are now doing."

But he also said, "There is, whether we like it or not, some fear . . . in some areas that our way of life is under pressure."

Raison did not point out that the vast majority of immigrants allowed into the country are white, that British's population is still 97 percent white or that nonwhite immigration has been cut so drastically by both Conservative and Labor governments since the 1960s that more blacks leave britain each year than enter it.

Some Conservative politicians believe the party's immigration policies have kept the support of people who might otherwise have been wooed by fringe white supremacist groups. They also argued today that tighter immigration restrictions are necessary to improve race relations by allaying the fears of whites.

But others fear the Conservatives have lost decisive nonwhite votes in big cities and that race relations are growing worse.