RAMALLAH, West Bank -- Enforcing a curfew, dozens of Israeli tanks patrolled the deserted streets of this West Bank town Wednesday and waged sporadic firefights with bands of Palestinian gunmen. A senior Palestinian security officer, an Israeli soldier and an Italian photographer were killed.

In the Gaza Strip, Israeli soldiers shot and killed a Palestinian after he opened fire on an Israeli vehicle in the Gaza Strip. Late Wednesday, two Palestinians entered Nahliel, a Jewish settlement northwest of Ramallah, and stabbed a settler, seriously wounding him, settlers and the military said.

The Israeli action in Ramallah was a continuation of its two-week-old military offensive; army chief Lt. Gen. Shaul Mofaz told a parliamentary committee about 20,000 Israeli soldiers are now stationed in the West Bank and Gaza Strip.

On the diplomatic front, Palestinians welcomed a U.N. Security Council resolution endorsing a Palestinian state. Israel praised elements of the measure, but did not comment on the statehood issue.

International diplomatic efforts have mounted as the Mideast endures its bloodiest stretch since fighting erupted nearly 18 months ago. However, there is skepticism they can quickly reverse the momentum of recent fighting, which has included multiple Palestinian suicide bombings and a half-dozen Israeli incursions into Palestinian areas.

More than 160 people have been killed on the Palestinian side and almost 60 have been killed on the Israeli side in March.

U.S. envoy Anthony Zinni was to arrive today for his third attempt to arrange a cease-fire or at least dampen the hostilities. The Bush administration told Israel and the Palestinians on Wednesday that Zinni would work for a truce and peace so long as he is making progress.

"He's got a lot of work to do, but if I didn't think he could make progress I wouldn't ask him to go," President Bush said.

Heated exchange

Secretary of State Colin Powell called Palestinian leader Yasser Arafat late Wednesday. Arafat aide Nabil Abu Rdeneh said they discussed Zinni's mission and Israel's occupation of Ramallah and other places in the West Bank and Gaza.

Many Israelis favor the tough military action against the Palestinians launched by Prime Minister Ariel Sharon, including the current mission, described as the largest Israeli military operation since its 1982 invasion of Lebanon. But in a stormy Cabinet session Wednesday, Sharon and Defense Minister Binyamin Ben-Eliezer exchanged heated words about how to conduct operations, Israeli media reported.

Sharon said the Cabinet had agreed that Israel should maintain continuous military pressure on the Palestinians for now and accused Ben-Eliezer of halting a number of military operations in Ramallah, the reports said, adding that Ben-Eliezer threatened to resign at one point.

In Washington, Bush criticized the forceful Israeli reaction to terror attacks, saying that while Israel has a right to defend itself, "the recent actions are not helpful."

Avoiding any perceptible tilt to one side, White House spokesman Scott McClellan called on the Palestinian Authority "to do everything it can" to stop attacks on Israel and chided Israel for attacks on the West Bank and in Gaza that injured civilians.

Dozens of Israeli tanks drove into Ramallah early Tuesday and enforced a curfew Wednesday in the largely deserted streets. In several locations, including downtown Manara Square, there were fierce gunbattles.