Civil rights, religious and political leaders, seeking to keep the spotlight on racial oppression in South Africa, will lead a symbolic funeral procession here Aug. 12 and hold a funeral ceremony at the State Department on behalf of South African blacks who have died since the start of a recent crackdown by the white-controlled government.

Randall Robinson, national coordinator of antiapartheid demonstrations at the South African Embassy here and in other U.S. cities, said the protest will commemorate those who have died during the Pretoria government's state of emergency.

In addition, he said, demonstrators will be urging President Reagan to sign legislation imposing economic sanctions against South Africa and to take even tougher measures against its apartheid policies. "We see the legislation as a small step," Robinson said. "Conditions in South Africa right now clearly warrant a stronger American response."

Robinson said the funeral procession will be led by numerous public officials and prominent religious, civil rights, artistic and entertainment figures, including Coretta Scott King, the Rev. Jesse Jackson, playwright Arthur Miller, singer Harry Belafonte, New York Mayor Ed Koch, Chicago Mayor Harold Washington, writer Harrison Salisbury and NAACP President Benjamin Hooks.

Episcopal Bishop John Walker, Rabbi Andrew Baker and representatives of the Roman Catholic and Islamic faiths will officiate at the funeral service at the State Department, Robinson said. Robinson said the demonstrators, some of whom will carry coffins, have decided to march from the Washington Monument to the State Department and to hold the funeral service "to make clear the Reagan administration's responsibility for events in South Africa before and since the declaration of a state of emergency."

In its most recent crackdown, the South African government issued a sweeping new ban on outdoor funerals with any political content in black townships. South African officials say the new measure is designed to defuse tensions in the townships by denying black protest leaders an important tool for stirring unrest. Opponents have warned that the ban closes one of the few remaining channels of legal protest.

Since Nov. 21, more than 3,000 antiapartheid demonstrators have been arrested at the South African Embassy here and in more than 20 other cities.

On Wednesday, House and Senate negotiators approved a package of economic sanctions against South Africa, including a halt to new U.S. bank loans. Reagan has expressed opposition to such sanctions, and Sen. Jesse Helms (R-N.C.) has threatened a filibuster against the legislation, which would delay final consideration until Congress returns from its August recess.