The international human rights organization Amnesty International said that the restoration of British authority in Rhodesia has not brought an end to human rights violations there.

The organization sent a telegram to the British governor of Rhodesia, Lord Soames, protesting what it termed "the relatively free rein left to the Rhodesian administration to maintain law and order on their own terms," according to a statement released in New York Thursday.

Amnesty said that martial law arrests continued to be made "under the procedures of the former illegal government," that people were still held incommunicado under 30-day detention orders and that prisoners held on political grounds by the previous government were still being held.

The telegram urged Soames to issue a "clear ban on torture." It said such a ban was needed because of "evidence that torture had been widespread under detention procedures still in use."

Amnesty acknowledged, however, that "considerable improvements" had been made in the human rights situation in Rhodesia since Soames took power last December. It estimated there were now "fewer than 2,000" martial law detainees.

But the organization urged Soames to realease all martial law detainees and allow outside access by groups such as the International Committee of the Red Cross to martial law detainees and political prisoners.

It also called for the British authorities to ensure that those arrested would be "properly charged or immediately released."

Meanwhile, the Manchester Guardian reported from Salisbury yesterday that Soames has received assurances from the two main guerrilla leaders, Joshua Nkomo and Robert Mugabe, that they will keep their men inside cease-fire assembly camps after voting ends in next week's elections.

The assurances came as British officials wrestled with the problem of deciding the future of both the 22,000 guerrillas gathered in 14 assembly areas and the 1,200-man Commonwealth monitoring force.

A spokesman for Soames said the British administration was encouraged by the introduction of joint patrols involving guerrillas and Rhodesian police at some assembly areas.

Eight clashes were reported between security forces and guerrillas who failed to observe the cease-fire however. Two guerrillas were killed in the clashes and elsewhere six black civilians were reported to have been murdered.