The Carter administration's dwindling hopes of arranging peace talks on Rhodesia received a sharp new set-back yesterday as Rhodesian war-planes struck again at African guerrilla installations a few miles from the center of the Zambian capital of Lusaka.

Viewing the new Rhodesian attacks deep inside Zambia as politically motivated and aimed in part at thwarting efforts for a peace conference, the State Department issued an angry denunciation of yesterday's Rhodesian raids, "which threaten to create an even more dangerous situation in southern Africa" and "add to the tensions, bitterness and distrust among the parties" to the 6-year-old guerrilla war.

The raids occurred as U.S. and British officials were renewing efforts to get the guerrillas and the "frontline" African states to settle internal differences and consider attending a peace conference with Rhodesian Prime Minister Ian Smith, who announced on Aug. 20 his willingness to participate in such talks in Washington.

"Smith cannot be ignorant of the effect these raids have on the ability of the others to come to the peace table," a senior U.S. official said yesterday, noting also that Zambian President Kenneth Kaunda, a key U.S. ally, is in the midst of a domestic political campaign.

Yesterday's bombing, carried out by at least two planes, wounded and killed about 100 people, according to initial reports.

The State Department's criticism, delivered by spokesman Kenneth Brown at a daily news briefing, was harsher in tone than the administration's criticism two weeks ago of the much larger Rhodesian attacks on a dozen black guerrilla camps in Zambia, which reportedly involved 1,500 African casualties.

Brown called yesterday's attacks "an unwarranted and deplorable escalation of the war," and said the United States "is deeply disturbed and strongly deplores these latest military actions."

A senior U.S. officials described the statement as a calculated political response to the political content of the raids, "which fly in the face of Smith's declaration about attending peace talks."

The two sets of raids are part of a series of setbacks that have thrown the administration off balance in its efforts, with Britain, to get Smith's biracial executive council to sit down and talk with the Patriotic Front guerrilla forces, led by Joshua Nkomo and Robert Mugabe.

Two months ago, the Carter administration was convinced that such talks were within reach, and watched with hope as Smith and Nkomo sat down in Lusaka for a secret meeting that one U.S. official now describes as "a testing of the water" for the full-scale conference.

At that point, Smith and the three black nationalist politicians who sit with him on the executive council were seen in Washington as the main holdouts. To draw both sides to the conference table, U.S. and British officials put together a new package of three "options" and other proposals that could be the basis of discussions.

The three options provided for different methods of dealing wit the date of elections and independence, but centered on the powere and length of time of service of a resident British commissioner who is to oversee the transition from rule by Smith and 250,000 white settlers to majority rule by the country's 6 million blacks, according to U.S. officials.

Behind Options A,B and C lay the hope that Smith and the Patriotic Front would be able to come to general agreement on a transitional power-sharing arrangement before going to a conference, according to involved officials.

But word of the Smith-Nkomo meeting was leaked to the press in Salisbury. Serious new wedges were driven between Nkomo and Mugabe, and sharp new splits developed within the frontline group.

In rapid succession, Nkomo's forces shot down a Rhodesian civilian airliner. Kaunda was forced by economic disaster to reopen his border with Rhodesia and resume imports through and from the rebel Brithish colony, and Smith succeeded in getting a visa to visit Washington.

The heavy first raid into Zambia occurred while Smith was in Washington, skillfully arguing that he had agreed to an all-parties peace conference because the U.S. and Britain had altered their positions, which he said had previously favored the guerrillas.

U.S. officials hotly dispute this contention, but acknowledge that Smith used it and his prsence in Washington during the first raids to stir strong suspicion of U.S. intentions within the African camp.

"Smith has succeeded in turning the tables in the last two months," one U.S. policymaker said ruefully. "About all we can do now is to wait for the dust to settle before we can see where to go."

The shift has pushed the United States back to putting its emphasis on getting the Patriotic Front and its supporters to agree to test Smith's new commitment to a peace conference.

Responses from some fof the frontline states in recent days have provided new encouragement, one U.S. officials reported yesterday, but an inconclusive summit meeting of the frontline states over the weekend and yesterday's raids appeared to be hampering the effort.

Some administration sources see the raids as a short-term military success that has hurt the guerrillas enough to give the Rhodesian army a breathing spell during the upcoming rainy season. But these same officials stress that the administration continues to be convinced that the raids in the long run will only radicalize the guerrillas and greatly increase the chances for Cuban or Soviet involvement in the final stage of a war they think Smith will still lose.