President Bush and South African President F.W. de Klerk proclaimed racial reform in South Africa to be "irreversible," but Bush noted he cannot yet move to lift economic sanctions against it.

Bush, following Monday's two-hour meeting with de Klerk, the first South African president to visit the United States in a half century, said specific conditions must still be met, like freeing political prisoners."You can count on us. We will not turn back," said de Klerk, who has cut away at his nation's racial segregation system of apartheid since becoming head of the white minority-ruled government last year.

Last winter, in his boldest move, de Klerk freed black leader Nelson Mandela, a political prisoner for 27 years, and legalized Mandela's African National Congress. In recent months, de Klerk opened talks with the ANC on a new constitution that would guarantee equal opportunity for all.

Until all the political prisoners are released, however, U.S. trade sanctions against South Africa, imposed in 1986 as punishment for apartheid, will remain.

Assistant Secretary of State for African Affairs Herman Cohen said de Klerk indicated steps are in progress to release remaining prisoners, and the White House read this to mean the release would take a few months.

It is unclear, however, when another key requirement to end the sanctions would be met - the lifting of a state of emergency. It remains in effect in the province of Natal, which has been rocked by black-on-black violence in recent months.

Under the law, Bush may ask Congress to lift or modify the trade sanctions if all political prisoners are freed and if any three of four remaining conditions are met.

Cohen said if four of the five conditions are met, Bush "would move to consult with Congress with the view toward modifying or suspending the sanctions."

In addition to ending the state of emergency, only one other condition has not yet been satisfied - repealing the Population Registration Act, which won't happen until a new South African Constitution is adopted.

The other two conditions, both met already, were legalization of political parties and the government's entering "good faith" negotiations with the ANC.