Prime Minister Fuad Saniora sharply denounced Hezbollah and its leader on Friday, a day after the guerrilla group's chief launched a scathing attack against the U.S.-backed government, promising to eventually bring it down.

The unprecedented trading of accusations and acid words between Saniora and Hezbollah leader Sheik Hassan Nasrallah marked a sharp turn in Lebanon's political crisis and further stoked the tensions between the two sides that threatens to tear the country apart.

"What we've seen yesterday was an unnecessary fit of anger and rudeness that we don't accept," Saniora told hundreds of supporters at his heavily fortified office complex where he has been holed up since the opposition launched street protests on Dec. 1 to bring down his government.

The two rivals had traded barbs in the past, mostly through aides or supporters, but their recent remarks descended into personal, direct attacks for the first time.

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In a rousing speech delivered Thursday night on huge screens in central Beirut, Nasrallah accused Saniora of conniving with Israel during its monthlong war with Hezbollah last summer. He claimed Saniora ordered the Lebanese army to confiscate Hezbollah's supplies of weapons — his sharpest attack on the prime minister since the August cease-fire that ended the fighting.

"Didn't the prime minister of Lebanon work to cut off the supply lines?" Nasrallah said. He added that government officials had asked American envoys to persuade Israel to destroy Hezbollah.

"Those are the ones responsible for the war, not the resistance," Nasrallah said.

The crisis has taken dangerous sectarian overtones, with Sunni Muslims largely supporting the Sunni prime minister against the Shiite Hezbollah. Christians were split between the two camps.

In his comments Friday, Saniora singled out the Hezbollah leader's attitude toward his opponents.

"You are not our Lord and the party is not our Lord," the Sunni prime minister said of Nasrallah, a Shiite cleric. "Who appointed you to say I am right and all else is false?"

"Is Israel here to fight it?" Saniora added.

He accused Nasrallah of threatening a coup and said the protests will lead nowhere. Emboldened by international support for his U.S.-backed government, Saniora has repeatedly insisted he would not give in to the demonstrations.

As he spoke inside the complex, loudspeakers at the square outside where opposition protesters have been camping out were airing a rerun of Nasrallah's speech in which he rejected strife between Shiites and Sunnis.

Despite the sharp words from both leaders, they both have say the door is still open for dialogue.

"Our hand and heart is open and we will continue," Saniora said Friday, speaking calmly and occasionally smiling. "We won't dig trenches in Beirut streets, we will build bridges of love among the Lebanese, Christian and Muslim."

Earlier Friday in downtown squares, Muslim prayers were held to show unity between Sunnis and Shiites.

"Your sit-in today, with God's help, will defeat the American project," said Fathi Yakan, who led several thousand worshippers in downtown Beirut. He was referring to what he described as American attempts to sow discord between Shiites and Sunnis in the Islamic world.

On the other side of the Lebanese political divide, the Sunni spiritual leader backed the U.S.-supported government warned that Hezbollah's demands won't be met.

"Bringing down the government and its prime minister in the street is a red line that we will never allow it," Sheik Mohammed Rashid Kabbani told worshippers at a downtown mosque.

Hezbollah has gained increasing political clout after the war, which began after Hezbollah guerrillas snatched two Israeli soldiers patrolling the south Lebanon border. It wants to topple Saniora's government because it has rejected demands for forming a national unity government that would give the pro-Hezbollah factions veto power in the Cabinet.

Saniora's allies, meanwhile, have accused Hezbollah of being influenced by Iran and Syria, which they claim want to destabilize Lebanon by supporting the militant group's plans to oust the government.

Responding to Nasrallah's speech on the confiscation of guerrilla arms, the Lebanese army issued a statement saying it received no orders from the government to block guerrilla weapons supplies during the summer war but said troops confiscated ammunition at one of the army's checkpoints. Hezbollah requested the ammunition be returned, but the army said it was up to the government to make that decision.

The U.N. Security Council has demanded Hezbollah be disarmed. But the job was left up to the Lebanese, because the U.N. peacekeepers deployed in southern Lebanon after the war, which number about 10,000, do not have the mandate to force Hezbollah to lay down its arms.