Secretary of State Rice is voicing an apparent policy shift on the disputed Shebaa Farms, a move designed to shore up support for Lebanon’s prime minister, Fouad Siniora, but one that could backfire, diplomats said.

In an unannounced visit to Lebanon yesterday during which she met with Mr. Siniora, Ms. Rice called on the United Nations to use its “good offices” to “deal” with the sliver of land known as Shebaa Farms. Supporters of the Shiite group Hezbollah say the area, which Israel captured from Syria during the 1967 war, is part of Lebanon. Ms. Rice’s comments came a day after she chided Israel for its settlement policies. They also followed reports that predicted a prisoner swap between Israel and Hezbollah, and came as Israeli and Syrian officials met with Turkish mediators.

At the United Nations, diplomats were caught off guard by Ms. Rice’s remarks on Shebaa. “For a long time, the Americans pressed the U.N. to keep a low profile on this issue. Now she wants the U.N. to resolve it,” a diplomat familiar with the issue, who spoke on condition of anonymity, said.

Israeli officials declined to comment on Shebaa, but the traditional government position has been that Israel’s complete withdrawal from all parts of Lebanon, including Shebaa, was certified by the United Nations in 2000. The area is strategically placed on high hills that abut Lebanon, Syria, and Israel, and Israel’s military has reportedly placed sensitive surveillance equipment there.

Prime Minister Olmert’s chief of staff, Yoram Turbovitz, and national security adviser, Shalom Turjeman, conducted a second diplomatic round of talks with unidentified Syrian officials Sunday. They discussed “real content,” Ynet quoted Israeli sources as saying. Previously, the possibility that Syria would officially declare Shebaa Farms part of its territory was offered by Damascus in the so-called Turkish track that was established between Mr. Olmert and President Assad of Syria through Ankara, according to several reports in Israel.

Hezbollah started saying Shebaa was an occupied Lebanese territory shortly after the 2000 Israeli withdrawal from Lebanon, as a pretext to maintain its armed “resistance.” Last year, Mr. Siniora called for Shebaa to be placed under the control of the United Nations.

“The United States believes the time has come to deal with the Shebaa Farms issue,” Ms. Rice told reporters in Beirut yesterday after meeting Mr. Siniora. Washington intends to press Secretary-General Ban to “lend his good offices” to resolve the dispute, she said, according to AFP. “The secretary-general should intensify his efforts.”

Mr. Ban submitted a report earlier this year that delineated the borders of Shebaa Farms, but did not determine who owns the land. Mr. Ban’s representative, Terje Roed Larsen, has argued that to change the status determined by U.N. cartographers in 2000, Syria and Lebanon must demarcate the border between them, as is called for by several council resolutions.

The pro-Hezbollah Lebanese newspaper al-Akhbar reported yesterday that a deal to exchange two Israeli soldiers — whose capture in 2006 triggered a war — for several Lebanese citizens in jail in Israel is imminent. Reports from Israel indicate some sticking points remain.

“What Condi said could backfire,” a U.N. diplomat who spoke about Ms. Rice’s comments on condition of anonymity said. “Instead of strengthening Siniora, it could boost Nasrallah.” The diplomat said that after being accused by allies of the Lebanese prime minister of igniting a war that achieved nothing but misery for the country, the Hezbollah chief could present the renewed Shebaa talks, as well as the heroic return of Lebanese “fighters,” as a victory none of his rivals could have achieved.