Nobel Peace Prize-winner Bishop Desmond M. Tutu invited white South Africans today to "join the winning side" in the black struggle against racial oppression.

Speaking at a thanksgiving service in a small church in the black township of Soweto where he serves as Anglican parish priest, Tutu addressed himself to the country's ruling white minority, saying: "If you think you can stop us from becoming free, you are going to be stampeded and overrun -- and we don't want you to be overrun.

"So come; come and join us. Come and join the winning side."

Meanwhile, Reuter reported from Durban that Britain told three South African dissidents encamped at its Durban consulate that they could have no further visits from their relatives and lawyers. The lawyers said the move showed that Britain planned to close the consulate within the next 48 hours so South African police could move in and arrest the three men.

Tutu stands at the vulnerable center of a rapidly polarizing society, still preaching racial reconciliation to two sides that seem to be moving toward violent confrontation.

Winning the Nobel prize has given a big boost to Tutu's prestige in the black community, as reflected in the rapturous welcome he has been given during a three-day return to South Africa from a sabbatical semester at the General Theological Seminary in New York, to which he returns Monday.

Today's thanksgiving service was the climax of this hero's welcome. Supporters had urged that the celebration be held in a sports stadium to make it a mass occasion, but Tutu, still shrinking from the political leadership role into which his enhanced status threatens to thrust him, insisted that it take place in his little red-brick parish church of St. Augustine's, set among Soweto's rows of monotonous houses.

It was an elaborate occasion all the same. The service was led by four priests and the champion African choir of Transvaal Province. St. Augustine's is a humble temple, with neither organ nor piano, but the sonorous voices of the choir, which wove a blend of high-church chants and African rhythms, and the enthusiasm of the jam-packed congregation, which danced to the rhythms and broke into ululations of praise, turned it into a spectacle that captivated the handful of whites who were present.