President F.W. de Klerk and Cabinet ministers were pleased and relieved at the historic peace pact struck between rival black anti-apartheid leaders Nelson Mandela and Mangosuthu Buthelezi, government officials said Wednesday.

The peace agreement, reached Tuesday, was also "sincerely welcomed" by liberal white parliamentary opposition Democratic Party. An official of the militantly anti-apartheid Pan Africanist Congress, which has accused Mandela and Buthelezi of being too accommodating of Pretoria, said "any peace efforts must be good."But all the parties also cautioned that the talk of peace had to be followed by an end to factional violence, which has killed thousands and stymied Pretoria's racial reform program. "We trust that (Mandela's and Buthelezi's) respective followers will act in the same spirit of reconciliation," Democratic Party spokesman Denis Worrall said.

African National Congress Deputy President Mandela and Inkatha Freedom Party President Buthelezi, meeting for the first time in 28 years, called jointly on their followers immediately to end the conflict which has killed some 5,000 people since 1987.

"There is no question that Mr. de Klerk is extremely happy with this," said a senior official in the Department of Constitutional Affairs, which has been managing de Klerk's racial reforms.

"The Cabinet was expecting a positive result from the talks and they are delighted and also very relieved that they seemed to work out," an adviser in the Ministry of Education and Training said. "Now they are looking for results."

De Klerk was unlikely to have any public comment on the meeting between the nation's two most politically active black leaders until his key Opening of Parliament speech Friday, spokesman for de Klerk Kobus Pieterse said.

Mandela and Buthelezi, after seven hours of talks, said they had come to a "solemn agreement" to call on "all our people, members of the ANC and the Inkatha Freedom Party, as well as our allies, to cease all attacks on each other with immediate effect."

They also pledged themselves to further talks, to monitor moves to peace, and suggested a neutral peace-keeping force to oversee the process of ending the strife.

The multi-tribal ANC, and to a lesser extent the nationally less popular and exclusively Zulu Inkatha, have alleged that the police and military bear much of the blame for the factional violence, saying they have taken sides and supported shadowy vigilante groups.

De Klerk has rejected this, blaming the fighting on traditional tribal differences. But Mandela has warned repeatedly that internecine fighting could dash hopes of substantive talks between Pretoria and the ANC on ending white minority rule.

De Klerk is expected to make further major concessions during his speech to Parliament Friday.