President Pieter W. Botha today expressed firm opposition to racial integration in South Africa and lashed out against foreign critics, including President Reagan.

"We will not satisfy the world because it measures with a double standard," Botha said, adding that "President Reagan, who has much to say in his mispronouncing way about apartheid, is shoving Indians into reservations and entrusting all the affairs affecting their lives to a single bureau."

Botha, who has presented himself as a reformist leader in this segregated country, intervened in a debate on the legal enforcement of separate living areas at a congress of his ruling National Party to insist that the law remain unchanged.

Supporting the position taken by conservative delegates in the debate, Botha also spoke in favor of equal but separate education for black, white, mixed-race and Asian South Africans. "The entire cultural life of our people and our children's educational rights" depended on the principle of separate residential areas, he said.

"While I support equal education for all, I say that the white child is also entitled to have his education within his own cultural surroundings," Botha said.

He insisted that residential segregation was not discriminatory, and said that attempts at racial integration in the United States and Britain had shown that when blacks moved into residential areas, whites moved out.

Integration also led to racial violence, Botha said, pointing to current rioting in Birmingham, England, and to recent clashes between Asians and blacks who live together in a township called Inanda, outside the South African port city of Durban.

It was the president's most unequivocal statement on the issue of social integration. He has appeared to be following a policy of scrapping what he calls the "unnecessary" aspects of the apartheid system of racial separation -- which are mainly its Jim Crow laws -- while retaining the essentials that keep political power in the hands of the white minority.

In his keynote address to the present congress, which is of the Cape provincial branch of the ruling National Party, Botha indicated Monday that he was trying to move toward the establishment of a federation based on ethnic and geographic "units" that he said would cease to be discriminatory but would still require segregation.

Today's debate began when reformist members at the congress in Port Elizabeth proposed abolition of the Group Areas Act that enforces separate living areas for whites, blacks, Asians and Coloreds, as people of mixed-race are called.

Jannie Momberg, a delegate who supported the proposal, said the enforcement of separate residential areas had become an anachronism since the revocation earlier this year of laws that prohibited sex and marriage across the color line.

Momberg, who is manager and mentor to a young athlete, Zola Budd, who caused a stir by taking British nationality to compete in the Los Angeles Olympics, said that after nine trips abroad he had concluded South Africa needed to make a bold gesture for change to offset its negative international image.

People in the United States and Europe were "sending us signals, even in the form of sanctions," Momberg said. "I plead with this congress that it must send a signal back to the world, showing that the National Party is determined to dismantle apartheid."

Botha then told Momberg and another delegate who supported him that they were "daydreaming" if they imagined South Africa could appease world opinion by making such reforms. Foreign critics were interested only in the abdication of white-minority rule, he said, then made his comment on Reagan.

European countries likewise discriminated against foreign migrant workers while making use of their labor, said Botha. "We are dealing with a hypocritical western world. We will follow the road of justice but not to the point of suicide, and the sooner we tell them that, the better."

Botha said the laws prohibiting sex and marriage across the color line had been repealed because they were discriminatory, but segregated living areas were not.

"It is not discrimination to protect black, Colored and Indian Asian communities in their own areas and to give them property rights which they did not have before," Botha said.

Meanwhile, there was tension at black schools throughout the country as they reopened for a new semester. Many of the schools, including most in Johannesburg's big township of Soweto, remained empty, indicating that militant students -- who have been in the forefront of the rebellion in the townships during the past 14 months -- intend to continue boycotts that began before the vacation.

Students forced a "homeland" leader, Cedric Pathudi, to leave a symposium that he was to address at a black university in Transvaal.

In Cape Town, six members of CBS and NBC television news teams were arrested and two were injured today when they tried to report a clash between police and Colored students at the University of the Western Cape.