Rhodesian black nationalist leader Joshua Nkomo said here yesterday he will not attend an Anglo-American conference of all parties involved in the Rhodesian constitutional dispute and intends instead to fight it out on the battlefield.

In his most categorical statement on the subject, Nkomo told a hastily convoked press conference at his home, "There can be no all-party conference in a war."

His clear and unequivocal rejection of the British-American conference leaves in grave doubt the possibility of holding one even if Rhodesia's white Prime Minister Ian Smith and his three black colleagues in the transitional government have finally agreed to attend.

Nkmono appeared to be speaking only as president of the Zimbabwe African People's Union (ZAPU), rather than as coleader of the Patriotic Front, the guerrilla alliance fighting to bring down the transitional government.

The other coleader, Robert Mugabe, has not yet made known his position on the conference following Smith's acceptance. But previously he has said he would go. He is head of the Zimbabwe African National Union (ZANU), which is based in Mozambique while ZAPU has its headquarters here in Lusaka.

However, Mugabe may well take the same attitude as Tanzanian leader Julius Nyerere one of Mugabe's key supporters, who said yesterday he would not support an all-party conference unless Smith first accepts year-old Anglo-American proposals as a basis of discussions. Smith has said he will attend only if there are no [WORD ILLEGIBLE]

Nyerere, chairman of the five "frontline" states, backing the nationalist guerrillas, was the first of his colleagues to speak out. His rejection means that Britain and the United States are not likely to get much support from the front-line presidents.

Even if Mugabe attended, a British-American conference without Nkomo would be doomed to failure and only serve to split the front, facilitating the very civil war the two Western powers are seeking to avoid.

Furthermore, there is little chance Smith will agree to hold talks alone with Mugabe, whom he regards as the more radical of the two front coleaders and a "Marxist terrorist." On the other hand, he has negotiated twice with Nkomo in the past and met secretly with him here in mid-August to discuss settlement terms.

Nkomo said Rhodesians carried out major attacks on his guerrilla camps inside Zambia on Friday following the one on a refugee center outside Lusaka. Thursday, in which 226 "noncombatants" were reported killed and more than 600 others wounded.

"The aggression is continuing," he told reporters, indicating that his guerrillas were fighting Rhodesian troops who landed around the campus.

He said the guerrillas had shot down seven Rhodesian aircraft during the fighting Friday.

"The all-party conference is on the battlefield," he said. "It's on now. They are attacking us and we have given them a very good brushing."

Apparently eager to make clear his stand on the conference, Nkomo explained that after six months of "debacles and massacres" of Africans in the war it is no longer possible to hold talks with leaders of Rhodesia's biracial transitional government. He described them as "dripping with . . . blood.

"Let me repeat why we will not go to an all-party conference," he said."Six months ago we agreed. We have fought the (Smith) regime to this day and the regime is in [WORD ILLEGIBLE] and the United States want us to save these people for their interests.

"No. Let us face them straight on the battlefield and we intend to get to Salisbury in the time given," he said, referring to a statement he made last spring that the guerrillas would win the war withing 10 months.

Nkomo told reporters the attacks Friday were carried out by Rhodesian bombers, fighter jets and helicopters.

Guerrillas shot down one Rhodesian Canberra bomber, three helicopters, one DC3 carrying 28 to 30 troops and two small spotter planes, he said. Guerrillas suffered only five injuries he claimed.