An officer was shot dead in a second day of clashes in the city of Kandahar, said provincial health director Qayum Pokhla. Two officers and 18 civilians were wounded, he said.

In Jalalabad, the largest city in the east, hundreds of people blocked the main highway for three hours, shouting for U.S. troops to leave, burning an effigy of President Barack Obama and stomping on a drawing of a U.S. flag.

More than 1,000 people set tires ablaze to block another highway in eastern Parwan province for about an hour, said provincial police chief Sher Ahmad Maladani.

The violence was set off by anger over the March 20 burning of the Quran by a Florida church — the same church whose pastor had threatened to do so last year on the anniversary of the Sept. 11 attacks, triggering worldwide outrage.

The protests, which began Friday, also appear to be fueled more broadly by the resentment that has been building for years in Afghanistan over the operations of Western military forces, blamed for killing and mistreating civilians, and international contractors, seen by many as enriching themselves and fueling corruption at the expense of ordinary Afghans..

Coverage of the trial of a group of U.S. soldiers charged with killing Afghan civilians and the publication of photos of some posing with dead bodies added to the anger.

Thousands of demonstrators in the previously peaceful northern city of Mazar-i-Sharif poured into the streets after Friday's Muslim prayer services and overran a U.N. compound, killing three U.N. staff members and four Nepalese guards.