A leading black Rhodesian politician said here yesterday that Prime Minister Ian Smith's reported acceptance of universal suffrage as part of an internal solution "must be tested very severely" by the world and by Rhodesia's African majority rather than being rejected immediately.

The Rev. Ndabanigngi Sithole added, however, that "any settlement has to be within the framework of the proposals" presented earlier this year by the United States and Britain to end the constitutional rebellion that began when Smith's white settler government seized power in 1965.

Smith has publicly riducled the Anglo-American proposals. He presented his offer last week to negotiate an internal settlement with black leaders inside Rhodesia as a way to bypass the British-American plan, which would involve the guerrilla forces of the Patriotic Front organization in a transfer of power to an independent majority backed government by the end of 1978.

In a newspaper interview published in Salisbury yesterday Smith said he would begin talks on Friday with Bishop Abel Muzorewa. Chief Jeremiah Chirau and a representative from Sithole who is currently touring the United States.

The Rhodesian Prime Minister said raids over the weekend into Mozambi-bique that resulted in a large number of African deaths should not deter the African Nationalists from taking part in the talks.

But in a letter to Smith. Muzorewa demanded an explanation for the raids and said he would not meet the white leader until he received assurances there would be no "similar massacres in the future." Sithole also denounced the raids in his comments here.

Speaking at the American Enterprise Institute yesterday, Sithole repeatedly sought to embrace more than one side of most issues, and declined to answer one hypothetical question about the use of force to achieve a settlement on the grounds "that I still have to go back to Salisbury."

The Methodist minister, who said that his political organization was paying for his trip to the United States, was paroled in 1974 after ten years in prison. One charge brought against him involved a plot kill Smith.

His opposition to the Patriotic Front guerrillas since he returned to Rhodesia in July has earned him the label of being a "moderate" now. He strongly attacked the Front during his talks at the Institute.

Repeating an earlier statement calling Smith's reported offer of "one-man, one-vote" a "major step forward," Sithole said Smith would have to release the country's remaining political prisoners and stop banning African nationalist publications if he wanted to appear sincere about reaching a settlement.

Meanwhile, one of the Patriotic Fron't leaders, Robert Mugabe, said in a broadcast on Mozambique radio that regular Israeli and South African troops took part in the Rodesian attacks.