Britain's Rhodesia negotiator, Lord Carver, met with black nationalist leaders in the Rhodesian capital of Salisbury yesterday and told reporters he was "much encouraged" by the talks.

At the same time Lord Carter was meeting with the nationalists, however, the leader of Rhodesia's white minority government, Prime Minister Ian Smith, said reports of progress in the Briton's meeting Wednesday with Rhodesian military officials were a "damn lie."

The British emissary has been meeting with all parties involved in the attempt to find a settlement of the Rhodesia dispute, which began in 1964 when the southern African colony declared its independence from Britain.

Earlier in the week, Lord Carver met in Dar es Salaam. Tanzania, with exiled black nationalists and the commanders of the guerrilla forces that have been fighting Smith's army from bases in neighboring countries.

A U.S.S. source in Washington said it was too early to tell whether Lord Carver's mission would succeed. He said the talks with nationalists in Tanzania had been inconclusive, and Smith was maneuvering for time "as be has been for more than 10 years." The source said Smith might still try to reach a settlement with moderate black leaders inside Rhodesia rather than dealing with the British and the guerrilla leaders.

Under the Anglo-American peace proposal for Rhodesia, Lord Carver would serve as administrator of the territory during a six-month transition to majority rule. He is accompanied on his current tour by Gen. Prem Chand, who would head a U.N. peacekeeping unit in Rhdoesia during that time, and the American ambassador to Zambia, Stephen Low.

Prime Minister Smith angrily disputed reports from the British delegation that Wednesday's meeting had been fruitful.

Speaking at a political rally in Bulawayo, Smith said: "No progress has been made - absolutely none." He said the minutes of the meeting indicated "a very clear consensus that ni progress could be made on a cease-fire until some political decisions have first been taken."

It was announced that Smith would meet with Lord Carver and Gen. Chand on Sunday before they leave for Botswana on the next leg of their southern African tour.

By constrast with Smith's remarks, the mood following Lord Carver's separate meetings with black nationalists Ndabaningi Sithole and Abel Muzorewa was optimistic.

Lord Carver told reporters he had reached "a very wide measure of agreement" with both men on the Anglo-American plan.

Sithole said he disagreed with the all-powerful role envisaged for Lord Carver during the transitional period and proposed a five-member administeration with Lord Carver as chairman instead.

About 4,000 supporters of Muzorewa, mostly women, staged a noisy demonstration outside Marimba House where yesterday's talks were held. They danced and chanted, holding aloft banners calling for "one man, one women, one vote."