UNITED NATIONS — As the speaker of the House, Rep. Nancy Pelosi, helped Syria to escape diplomatic isolation yesterday by saying she conveyed to Syria’s President Al-Assad a “message” from Jerusalem about Israel’s readiness for peace negotiations, Prime Minister Olmert denied he had given her any such message.

The confusion seemed to add weight to Ms. Pelosi’s critics, including President Bush who had said a day earlier that her trip to Syria only “sends mixed signals,” and a presidential hopeful, Governor Romney, who also said yesterday that the trip sent “the wrong signal to the people of Syria and to the people of the Middle East.”

While Washington politicians debated, a U.N. spokeswoman, Michele Montas, confirmed yesterday that Secretary-General Ban was also set to visit Damascus soon. Mr. Ban returned on Monday from a week-long tour of the Middle East. According to aides, he intends to go again at the end of the month, this time to Damascus only.

Mr. Ban’s announcement came as Lebanese legislators petitioned him yesterday to push harder for the establishment of an international court to try suspects in the assassination of a former Lebanese prime minister, Rafik Hariri.

Officials close to Mr. Assad are considered top suspects in the assassination, and their Lebanese allies fear exposing them to an international trial. Pro-Syrian politicians in Lebanon, according to the letter that was sent to Mr. Ban by a majority of 70 members of parliament, have led to an “impasse,” rendering the establishment of the tribunal impossible.

“We were very pleased with the reassurances we received from” Mr. Assad “that he was ready to resume the peace process,” Ms. Pelosi said yesterday after meeting Mr. Assad. “He was ready to engage in negotiations [for] peace with Israel.”

The meeting she and five other House members conducted with Mr. Assad yesterday “enabled us to communicate a message from Prime Minister Olmert that Israel was ready to engage in peace talks as well,” Ms. Pelosi said.

But according to a “clarification” posted on Mr. Olmert’s official Web site, there was no such communication. “Although Israel is interested in peace with Syria, that country continues to be part of the axis of evil and a force that encourages terror in the entire Middle East,” it read. “What was communicated to the U.S. House speaker does not contain any change in the policies of Israel, as was communicated to other foreign leaders.”

For “serious and genuine” negotiations to begin, Mr. Olmert added, “Syria must cease its support of terror, cease its sponsoring of the Hamas and Islamic Jihad organizations, refrain from providing weapons to Hezbollah and bringing about the destabilizing of Lebanon, cease its support of terror in Iraq, and relinquish the strategic ties it is building with the extremist regime in Iran.”

In Israel, the episode was seen as related more to Washington partisan rivalries than to Middle East diplomacy. “This has to do with internal American politics,” the former Israeli ambassador in Washington, Daniel Ayalon, told The New York Sun.

Mr. Ayalon, who maintains close ties with top officials in both capitals, added that meetings with Ms. Pelosi in Jerusalem were conducted merely “out of courtesy and respect for her office.” No significant diplomatic message was conveyed to Syria through her delegation, he added.

Mr. Ban raised the possibility of peace negotiations with Israel during a private meeting with Mr. Assad in Riyadh, Saudi Arabia, last week, but Mr. Assad mostly talked about “the issue of the Golan Heights,” according to U.N. diplomat who spoke on the meeting on condition anonymity.

U.N. aides and top Security Council members scrambled yesterday to address the concerns of the Lebanese parliamentarians, raised in the petition that was delivered by hand to Mr. Ban’s envoy in Beirut on Monday.

The legislators asked the secretary-general and the council to use “all alternative measures under the U.N. charter to guarantee the establishment of the tribunal,” according to a senior U.N. official who briefed reporters yesterday on condition of anonymity.

A tribunal “with international character” was proposed by the Security Council last year as a mechanism to assure impartiality at trials of suspects in the Hariri assassination and related political killings. The council asked for approval of the Lebanese government, including parliamentary ratification. While Prime Minister Siniora’s Cabinet approved the tribunal, pro-Syrian forces and Hezbollah politicians have prevented a parliamentary vote.

Acting on yesterday’s letter, the Security Council may now enforce the establishment of a tribunal through a new resolution based on Chapter 7 of the U.N. Charter, which makes its decision binding.

“We fully support the immediate establishment of the tribunal,” a spokesman for the American mission to the United Nations, Ben Chang, said.