Damascus, Syria ? Secretary of State Colin Powell took soundings in Syria and Lebanon on Monday on a proposed Mideast peace conference and warned leaders of the two nations that guerrilla attacks on Israel could spill over into a wider conflict.

Powell said in Damascus that he wanted Syrian President Bashar Assad’s assessment on “a way forward to negotiations” to settle the Arab-Israeli conflict.

He also took up with the Syrian leader, as he had with Lebanese leaders in Beirut earlier in the day, “some of the danger with respect to firing over the Blue Line,” the U.N. drawn border between Lebanon and Israel.

Hezbollah guerrillas have fired rockets almost daily into Israel. Syria, which holds effective political and military control over Lebanon, is considered the militia group’s patron, helping to funnel weapons from Iran to southern Lebanon.

On the diplomatic track, Powell is trying to measure sentiment for an international peace conference. Among the versions is one by Israeli Prime Minister Ariel Sharon that would include Saudi Arabia, Syria, Lebanon and the Palestinians _ without Yasser Arafat.

In Beirut, Powell met with Foreign Minister Mahmoud Hammoud and then President Emile Lahoud and Prime Minister Rafiq Hariri, warning that violence along the border between Lebanon and Israel could spread the conflict throughout the region.

“It is critical for those who support peace to act immediately to stop attacks across the border,” Powell said.

Hammoud, in a strongly worded anti-Israeli statement, suggested there was a need for some “objectivity” about the attacks, which he described as resistance to Israeli occupation.

“Israel is responsible for the current escalation because it blocked all efforts seeking peace and has rejected all international resolutions,” he said.

Powell also is discussing the growing possibility of an international Mideast peace conference, an idea proposed by Israeli Prime Minister Ariel Sharon.

Thousands of Lebanese and Palestinians demonstrated on the airport highway as Powell arrived in Beirut. Protesters burned American and Israeli flags and shouted: “Oh, God!, Powell Out!” and “Death to America! Death to Israel!”

Powell is urging both Lebanon and Syria to restrain Hezbollah guerrillas whose cross-border attacks on Israel are causing growing international concern.

The Lebanese officially support Hezbollah’s shelling of Chebaa Farms, a small disputed enclave held by Israel along the border after a withdrawal from southern Lebanon. The attacks have been an almost daily occurrence, but there was no shelling Sunday on the eve of Powell’s visit.

U.S. officials said the stops in Lebanon and Syria were focused primarily on Powell’s concern that the attacks from Lebanon could escalate even as Israel and the Palestinians are locked in a bloody conflict. But the sub-theme of the sessions is the possible international peace conference.

The officials, speaking on the condition of anonymity, said the idea is in a preliminary stage, but they would not rule the staging of a conference based on land-for-peace proposals.

Syria is seeking Israeli withdrawal from the Golan Heights, a strategic high ground Israel won in the 1967 Mideast War; several U.S. efforts to broker an agreement have failed.

Meanwhile, senior American officials will meet with Palestinians close to Arafat to discuss how to advance peacemaking on that troubled front.

Powell is struggling to persuade Sharon to pull his forces from the West Bank and Palestinian leader Arafat to curb violence.

Progress is slow on both fronts, and Powell may extend his Middle East trip to keep at it a few days longer.

While he is seeking to curb Hezbollah, Lebanon and Syria are likely _ as other Arab leaders have been _ to push him to pressure Israel to end its drive on the West Bank.

State Department spokesman Richard Boucher said the situation along the border between Israel and Lebanon was of “urgent and serious concern.”

The State Department has branded Hezbollah as a terrorist organization and has asked Iran, through intermediaries, as well as Syria and Lebanon to clamp down.

On Sunday, Arafat told Powell that he was committed to trying to end violence, but that Israel first must withdraw its troops from the West Bank. Attacks by Palestinian suicide bombers have killed 33 Israelis and injured scores more since the start of the Israel offensive. Hundreds of Palestinians have died.

Powell, after shuttling back to Israel for a meeting in Tel Aviv, then pressed Sharon for a complete pullback, a U.S. official said.

Sharon is resisting. His spokesman Raanan Gissin said the prime minister renewed his proposal for an international peace conference.

Saudi Arabia, Syria and Lebanon would participate along with Israel. Saudi Crown Prince Abdullah has offered peace and security to Israel in exchange for the land the Arabs lost in the 1967 Mideast war.

A senior U.S. official, speaking on condition of anonymity, said Powell and Sharon had discussed the idea and how it might be done “as part of a way to move forward politically.” But, he said, “there is still more discussion necessary.”

Arafat, 72, appeared in good health as he met with Powell in his rocket-scarred headquarters, which is surrounded by Israeli tanks and troops. Arafat has been under pressure that is “unreal for an old man like him,” said Zeid Abu Shawish, a Palestinian doctor in the compound.

Powell was driven to the besieged compound in a motorcade of armored-plated SUVs, shielded by U.S. security personnel with submachine guns.

The headquarters showed the effects of Israeli bombardment. A gaping hole marred the facade and the walls were blackened with bullet marks.

A senior aide, Saeb Erekat, said Arafat stood by his commitments, including an end to violence. But, Erekat said after the three-hour meeting, that meant “once the Israelis complete the withdrawal we will, as Palestinians, then carry out our obligations.”

Arafat complained bitterly and extensively to Powell about Israel’s military thrust into Palestinian-held towns and villages, and especially its actions in Jenin and a refugee camp in the town.

Powell, in a brief statement to reporters, called his meeting with Arafat useful and constructive.