Beirut, Lebanon ? Prime Minister Fuad Saniora on Friday accused Hezbollah’s leader of threatening a coup in an unusually harsh exchange between the two rivals that stoked tensions as the Shiite guerrilla group escalated its attempts to oust the government.

Saniora spoke to hundreds of supporters in his fortified office, where he has lived for more than a week. Outside, pro-Hezbollah demonstrators in a nearby square replayed on loudspeakers a Thursday night speech in which their leader, Sheik Hassan Nasrallah, accused the prime minister of siding with Israel during the July-August war.

The prime minister said Nasrallah “is threatening a coup and his statements carry all the seeds of dissension and threat.”

Saniora criticized the Hezbollah leader for his attitude in the speech, in which he accused the prime minister of being “stubborn” and said members of the government were responsible for the war, which began after Hezbollah seized two Israeli soldiers.

“Who appointed you to say ‘I am right and all else is false’?” the prime minister asked.

A sunni sheik, left, and a shiite sheik lock hands during Friday prayers on the eighth day of an open-ended protest to force the resignation of Lebanese Prime Minister Fuad Saniora in front of the Mohammed al-Amin mosque in downtown Beirut, Lebanon. Shiites and Sunnis called on supporters to turn out for a mass downtown noon prayer lto show Muslim unity

Saniora, who has received strong Western and Arab support, repeated that Hezbollah’s protests, now in their eighth day, would not force his resignation. The pro-Syrian Hezbollah and its opposition allies have called for a huge demonstration Sunday, saying it will mark an escalation in their attempts to oust the U.S.-backed premier.

Hezbollah and its allies began demonstrating after Saniora rejected their demands for a third of the Cabinet’s seats – an effective veto.

Six pro-Hezbollah ministers resigned from the Cabinet last month over Saniora’s refusal to accept the demand, depriving the government of any Shiite representation.

The political division has taken dangerous sectarian lines, with most Sunni Muslims supporting the Sunni prime minister and Shiites backing Hezbollah. Christian factions are split between the two camps.

Hezbollah has not said what it plans to do next, but some Lebanese believe it might call for civil disobedience or escalate street protests, disrupting vital utilities such as the Beirut airport. So far, however, Nasrallah has stressed that his supporters must demonstrate peacefully.