Israeli officials on Tuesday said their military offensive in Lebanon could last several more weeks and possibly involve large numbers of ground forces — casting doubt on the effectiveness of growing diplomatic efforts to broker a cease-fire.

Prime Minister Ehud Olmert told a visiting U.N. delegation that "Israel will continue to combat Hezbollah and will continue to strike targets of the group" until captured soldiers are released and Israeli citizens are safe from attacks.

Foreign Minister Tzipi Livni said diplomatic efforts were under way, but that a cease-fire would be impossible unless Israel's three captured soldiers were returned unharmed and Lebanese troops were deployed along the countries' border with a guarantee that the Hezbollah militia would be disarmed.

Livni's remarks, which came after she met with a U.N. delegation touring the region, were the first indication that both sides in the weeklong conflict were making significant efforts to end Israel's bombardment of Lebanon and Hezbollah's rocket attacks on Israel, which have killed at least 220 people in Lebanon and 24 in Israel.

But Maj. Gen. Udi Adam, the head of the Israeli army's northern command, said the offensive against Hezbollah, which has mostly been limited to Israel's air force and navy, would continue.

"I think that we should assume that it will take a few more weeks," he told Israel's Army Radio.

The army's deputy chief of staff, Maj. Gen. Moshe Kaplinski, also told Israel Radio that Israel has not ruled out deploying "massive ground forces into Lebanon."

An Israeli Cabinet minister, Avi Dichter, meanwhile, said Tuesday that Israel may consider a prisoner swap with Lebanon to win the release of two soldiers captured by Hezbollah, but only after its military operation is complete.

"If one of the ways to bring home the soldiers will be negotiations on the possibility of releasing Lebanese prisoners I think the day will come when we will also have to consider this," the public security minister told Israel's Army Radio.

Meanwhile, Hezbollah fired more missiles at Israel on Tuesday, hitting the city of Haifa and several other locations in northern Israel but causing no injuries. Hezbollah has fired hundreds of rockets at northern Israeli towns from the Lebanese border since fighting began on July 12, forcing hundreds of thousands of Israelis to take cover in underground shelters or flee to the south.

Despite those attacks, Israelis strongly support the military operation against Hezbollah, a poll found. Published in the Israeli daily Yediot Ahronot, it said 86 percent of Israelis believe the operation is justified, 81 percent want it to continue and 58 percent say it should last until Hezbollah is destroyed. The poll had a margin of error of 4.2 percent.

Nevertheless, Livni said, "We are beginning a diplomatic process alongside the military operation that will continue."

"The diplomatic process is not meant to shorten the window of time of the army's operation, but rather is meant to be an extension of it and to prevent a need for future military operations," she told reporters.

Israel's two-front offensive against Islamic militants began on June 25 when Hamas-linked guerrillas in the Gaza Strip carried out a cross-border attack on a military outpost in Israel, killing two soldiers and capturing one. Lebanon's Hezbollah guerrillas joined the fray on July 12, attacking a military patrol on the border in northern Israel, killing three soldiers and capturing two.

Israel's offensive to date has been carried out mostly by air and sea. Israel has been reluctant to use ground forces because of memories of its ill-fated 18-year occupation of south Lebanon that ended in 2000.

On Tuesday, Foreign Minister Livni signaled Israel might be willing to accept a temporary international "stabilization" force in south Lebanon to bolster the 2,000-strong force already there. Western nations have been proposing the beefed-up force as part of a possible cease-fire agreement — an idea Israel had previously brushed off.

In Belgium, U.N Secretary-General Kofi Annan any international stabilization force that must be "considerably" larger and better armed than the U.N.'s current force. He said details of the proposed force's size and rules of engagement have yet to be worked out.

Livni said securing south Lebanon "requires activity by the Lebanese government, with the oversight (and) assistance of the international community." She said Israel's experience with the current U.N. force was "not satisfactory" and that it prefers no such force in the long-term.

In recent days, Israeli officials have sent conflicting signals about whether Israel would demand Hezbollah's immediate disarmament as a condition for a cease-fire. Livni's comments indicated Israel would accept future disarmament, provided that Lebanon immediately deploy its own troops along the border to prevent any future rocket attacks against northern Israel.

Livni said that Israel wants to prevent Iran and Syria from arming Hezbollah in the future. The two countries are prime sponsors of the militia, raising concerns that their involvement could cause a wider regional conflict.

U.N. negotiator Terje Roed-Larsen told reporters in Jerusalem after meeting Livni that "concrete ideas" had been presented to the Israeli government to solve the crisis, and that Israel would deliberate on them in the coming days. "I think both parties agreed that it is necessary to have a political framework in order to reach, eventually, a cease-fire," Roed-Larsen said.

He did not provide any further details on the proposals.

The U.N. team, led by Annan's special political adviser Vijay Nambiar and Mideast envoy Alvaro de Soto and including Roed-Larsen, arrived in Jerusalem Monday night to try and broker an end to the week of fighting.

• A brief history of the Lebanese-Israeli conflict.

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