The African National Congress said Saturday it will boycott negotiations with the government on South Africa's political future but will continue current talks to resolve differences between the two sides.

A government statement said the ANC's actions were "irresponsible."The black opposition group reaffirmed past statements that it would not take part in negotiations on a new constitution until the government met demands listed in an April 5 ultimatum, which included the firing of Cabinet ministers in charge of security forces and laws banning spears carried by Inkatha Freedom Party members.

The secretary-general of the ANC, Alfred Nzo, said government-ANC "working groups" set up in the past year to help clear the way for negotiations will continue meeting. He said the two sides also will continue talks aimed at resolving their impasse over violence in black townships.

The violence has involved the ANC and the rival Inkatha party, the nation's two leading anti-apartheid black organizations. They have deep tribal and ideological differences and more than 6,000 blacks have died in their bitter power struggle that began in 1986.

"Until such a time as progress is made in regard to these demands, the ANC will not involve itself in constitutional negotiations with the government, or in any all-party congress to discuss the mechanism for drawing up a new, democratic constitution," said an ANC statement read by Nzo.

ANC and government leaders have met intermittently for the past year in an attempt to clear the way for formal negotiations on ending white-minority rule.