Rhodesia's Executive Council yesterday summarily dismissed a black Cabinet minister in a move likely to affect the transitional government's credibility both at home and abroad.

Byron Hove, the cominister of law and order, was fired for suggesting publicly that majority rule should involve greater black participation in the polce and judiciary.

Senior U.S. officials said the action raised serious doubts about "the honesty and intent of the Smith regime" to turn the country to black majority rule in a "meaning way" by the end of the year.

Prime Minister Ian Smith, leader of Rhodesia's white community, made an agreement with three black leaders last month to form a multiracial transition government and lead the country to majority rule. The United States has not endorsed this so-called "internal settlement."

"The reason we couldn't endorse the settlement was that we were skeptical about their intention to turn Rhodesia to real majority rule," one senior U.S official said yesterday. The firing of Hove "is a good example that our doubts were well founded," he added.

The internal settlement has not won internation recognition. Moreover, the transitional government is engaged in a civil war waged by black guerrillas based outside Rhodesia.

Hove, 38, is a tall, dapper lawyer who has lived outside Rhodesia for 12 years, first working for the Organization of Africa Unity in Adis Abbaba, Ethiopia and for the past several years as a lawyer in London.

He returned to Rhodesia three weeks ago after he was offered the justice post by Bishop Abel Muzorewa, one of the three black leaders who made the pact with Smith.

American officials described Hove as an able lawyer whose political views are "moderate.'

If they (white Rhodesians) can't accept him, "one official said, "how are they going to make hard decisions down the road."

In a interview with the Washington Post earlier this week , Hove said that "to win over the black people, we have to be seen to be making changes. We can't just sing praises to the settlement, we have to do something."

Hove's public demands for such immediate signs of change focused on increased recruitment of blacks for high-level civil service jobs, especially in the police and judiciary. "Majority rule has to implemented," he said in the Post interview.

But Hove's demands for "positive reverse discrimination" has upset not only an already jittery white population but also Muzorewa and his black associates in the Executive Council.

There was speculation that Hove may be promoting personal ambitious by striking the middle ground between the "internal" black leaders, who advocate gradualism, and the radical Patriotic Front guerrilla leaders, who are fighting the Smith government.

Hove said in the Post interview that he is "in intensive contact" with Patriotic Front guerrillas. Having once described Smith as the "Hilter of southern Africa", Hove has become something of a hero to black Rhodesians for his outspokeness.

Before his dismissal, he was urged by the government to publicly apologize for his remarks. He refused. Yesterday's edition of the largest black newspaper in Rhodesia, the National Observer, reported that it had received numerous telephone calls and letters supporting Hove's stand.

Hove's dismissal was viewed as a considerable setback for the transitional government. It complicates the already tangled situation in Rhodesia. An Anglo-American plan intended to bring all black nationalist groups to an election appears to be stalled. The guerrillas are continuing to press on with their armed struggle, and the transitional government has found it hard going to generate popular support among the 6.7 million blacks.

From the government's point of view, Hove's statements also raised the prospect of right-wing backlash as some conservative whites are still hoping to convince white voters to reject a new constitution at a ballot Smith has promised to hold before Dec. 31.