UNITED NATIONS — In a snub to America, the closest ally of Zimbabwe’s president sent a low-level diplomat to a U.N. Security Council session organized by Secretary of State Rice to address the violence surrounding the run-up to next week’s election in the African nation.

South Africa’s cold shoulder, diplomats said, is the latest demonstration of the delicate diplomatic dance around Zimbabwe, where regional alliances and sensitivities among the world powers have prevented outsiders from intervening to stop a once-thriving country from descending into a failed state led by an aging dictator who refuses to relinquish his hold on power.

Twelve bodies were found yesterday across the country, most of them showing signs of torture, according to a report by Amnesty International. The victims appear to have been abducted by supporters of President Mugabe’s Zanu-PF party, the report said. At least 60 members of the opposition have been killed in recent weeks.

“I think that the mood in the room was one of extraordinary concern and a desire to have President Mugabe hear that there is great international concern about what he is doing to his country,” Ms. Rice said of yesterday’s meeting.

America, which holds the Security Council presidency this month, is pushing for an official council meeting on Zimbabwe early next week. But officials acknowledged that they do not expect the council to unite behind a demand that more outside observers be allowed to oversee the runoff presidential vote on June 27, let alone threaten any punitive action against Mr. Mugabe.

Through complicated negotiations with Mr. Mugabe, Secretary-General Ban managed to secure entry for a U.N. envoy, who has conducted a four-day tour of the country and met with government and opposition officials, including Morgan Tsvangirai, who won the first round of presidential voting. But the envoy, Haile Menkerios, a South African citizen, is not likely to brief the council in person next week. Mr. Menkerios, whose Zimbabwean mission ends Friday, is scheduled to travel elsewhere, returning to his New York office at the earliest July 7, according to U.N. officials.

Yesterday, Ms. Rice convened a roundtable discussion for Security Council members, Zimbabwe’s neighbors, and nongovernmental organizations. “We heard concerns that the current conditions are not such in which free and fair elections can possibly be held,” she said, in Washington’s strongest condemnation to date of the situation in Zimbabwe.

America, Britain, and their allies have long pushed for a Security Council discussion on the growing political crisis in Zimbabwe. But South Africa, which holds a two-year seat on the 15-member council, has flexed its muscles and, along with permanent council members China and Russia, prevented any meaningful action that could hurt Mr. Mugabe.

America invited foreign ministers to join Ms. Rice for an unrelated public council debate yesterday on sexual violence in conflict areas. While only few high-level officials chose to participate, South Africa sent its foreign minister, Nkosazana Dlamini Zuma. But later, when the session on Zimbabwe began, Ms. Zuma was conspicuously absent.

Ms. Zuma “was invited for a meeting about rape in time of war,” the South African ambassador to the United Nations, Dumisani Kumalo, said. “I sent my deputy” to the Zimbabwe session, he added.

Ms. Rice then requested a private meeting with Ms. Zuma. After the meeting ended, Ms. Rice declined to comment on the apparent South African snub. “Foreign Minister Zuma and I have a very good relationship, and we want the same thing in Zimbabwe,” she told reporters when she emerged from the parley.

The South African president, Thabo Mbeki, is said to have some influence over the government of Zimbabwe, but he has viewed Mr. Mugabe as an ally in the war against colonialism and apartheid. When Britain held the Security Council presidency in April, Prime Minister Brown sought a meeting with Mr. Mbeki on the crisis in Zimbabwe, but Mr. Mbeki declined, opting instead for a short chat with Mr. Brown in the corridor.

At a press conference later, Mr. Mbeki spoke of “loud diplomacy,” a term reporters interpreted as a reference to Mr. Brown’s conduct on Zimbabwe. The Times of London described the incident as a “diplomatic snub” of Mr. Brown.