KABUL, Afghanistan — Armed with rocks, bricks, pistols and wooden sticks, protesters angry over the burning of Qurans at the largest U.S. base in Afghanistan this week took to the streets in sometimes lethal demonstrations in a half dozen provinces Wednesday that left at least seven dead and many more injured.

The fury did not appear likely to abate any time soon. Members of the Afghan Parliament called on Afghans to take up arms against the U.S. military, and Western officials said they feared that conservative mullahs might urge people to violence at the weekly Friday prayers, when a large number of people go to mosque.

“Americans are invaders and jihad against Americans is an obligation,” said Abdul Sattar Khawisi, a member of Parliament from Parwan province’s Ghorband district. “I am calling upon all the mullahs and the ulema to urge the people from the pulpit to wage jihad against Americans.”

President Hamid Karzai is scheduled to address both houses of Parliament this morning.

With the mood tense across the capital, Karzai made his first public statement on the incident, condemning the Quran burnings and setting up an ad hoc committee of mullahs and senior religious figures to investigate it.

He said the preliminary investigation showed that U.S. “soldiers had burned four copies of the Holy Quran.” It was not clear if other copies were damaged but not actually burnt. Earlier reports from elders who visited Bagram Air Base on Tuesday and saw some of the Qurans indicated that between 10 and 15 were damaged to varying degrees.

The U.S. efforts here are at a crucial stage, as they are attempting to negotiate a strategic partnership agreement with the Afghans and to pave the way for peace negotiations. Aware of the damage the Quran burnings can cause, U.S. diplomats and military officials met with Karzai and spoke to senior Afghan government and religious figures in an attempt to tamp down their anger, said Mark Thornburg, the acting spokesman for the U.S. Embassy.