President Jose Eduardo dos Santos had made the offer personally to Jonas Savimbi earlier this year.
Savimbi had said he did not want the job if it were mainly ceremonial, and UNITA rebels followed that up with a statement Tuesday ''categorically'' rejecting the post.
The vice presidency would control mining, trade, health and tourism ministries. The formation of a coalition government and the merging of rebel and government armies are seen as cornerstones of U.N.-brokered peace accords signed in 1994.
Another vice president's post was to be filled by dos Santos' Popular Movement for the Liberation of Angola. Dos Santos' four-year term ends in the fall, and UNITA's rejection of a job in the government could leave the rebels free to press for new elections.
UNITA -- the National Union for the Total Independence of Angola -- first went to war with the government on the eve of independence from Portugal in 1975.
Fighting since then has killed 500,000 Angolans, and left millions more maimed, homeless and threatened by disease and starvation.
The UNITA statement left open the possibility of further negotiations with the government and U.N. mediators on the issue.
=A9 Copyright 1996 The Associated Press