The Rhodesian nationalist Patriotic Front, which is waging a guerrilla war against Rhodesia's white-ruled government, denounced Britain and the United States yesterday for "connivance and assistance" in negotiations for black majority rule now being held in Salisbury, the Rhodesian capital.

"We are resolved in our total condemnation of the sellout agreement reached in Salisbury," Patriotic Front co-leadrs Joshua Nkomo and Robert Mugabe also said in a statement issued after a two-day meeting here.

The front has boycotted the talks between white Rhodesian premier Ian Smith and leaders of three other black nationalist groups. They have reached preliminary accord on the framework of a constitution leading to black majority rule through universal suffrage elections in Rhodesia.

British and U.S. officials initially said no Rhodesian settlement could exclude the Patriotic Front but have since issued more favorable statements expressing qualified support for the Salisbury agreement.

The Rev. Ndabaningi Sithole, leader of the African National Council which has been taking part in the talks, appealed meanwhile to the Organization of African Unity (OAU) and the United Nations to await the outcome of the Salisbury negotiations before passing judgement. He said he was satisfied the agreement "does help us, African and the rest of the world to solve the problem that has bedevilled our country for the past 13 years."

An OAU, meeting in Tripoli, Libya, has passed a resolution supporting the Patriotic Front and rejecting the Salisbury talks as fraudluent.