The British government and Jewish community reacted with dismay after the US black political leader, Mr Louis Farrakhan, yesterday won a legal victory overturning a long-standing ban on him visiting the UK.
Fears were raised over the ruling's potential to threaten racial harmony in Britain.
The controversial head of the Nation of Islam has been excluded from Britain since 1986 by successive home secretaries because of concern that his presence could lead to public disorder following anti-Semitic remarks he has made in the past.
Chicago-based Mr Farrakhan (67), who suffers from prostate cancer, successfully challenged last November's personal decision by the then home secretary, Mr Jack Straw, to continue the exclusion order. Mr Justice Turner announced at London's High Court yesterday: "My decision is that it be quashed."
He said it was "a matter of extreme personal regret" that pressure of work had prevented him from giving his reasons, but they would be provided on October 1st. He ordered a "stay" on his decision taking effect until then, which means that Mr Farrakhan will not be able to plan an immediate visit to the UK.
The Home Office Minister, Ms Beverley Hughes, said the government was very disappointed by the ruling and would be considering an appeal.
"We believe that it is the Home Secretary's right to defend the social cohesion and racial harmony of this country," she said.
The chairman of the Holocaust Educational Trust, Lord Janner, said: "This is a sad day for all of us in Britain who work for good race relations.
"We fear that if he repeats the sort of racist remarks about Jewish people that he has made in the past, he could cause unwanted tensions.
"I'm especially concerned that we continue to keep the excellent relations between the Jewish and Muslim communities of this country, not least because of the possible fall-out of Middle East miseries."
Mr Hilary Muhammad, UK spokesman for the Nation of Islam, welcomed the judge's ruling, saying: "Now the citizens of the UK will have a chance in the near future to see, hear and judge the honourable minister, Louis Farrakhan, for themselves".
The US black civil rights leader, the Rev Jesse Jackson, yesterday applauded the High Court's decision to allow Mr Farrakhan into the UK. Speaking to the BBC, he said the Nation of Islam leader was coming to Britain "as a source of reconciliation and peace".