There was also deadly violence in the east on Wednesday. A suicide bomber crashed a car into a police bus, killing 14 people and wounding 16, said Zemeri Bashary, a spokesman for the Interior Ministry. Most of the casualties were police officers, he said.

There was no claim of responsibility, but it matched the pattern of Taliban attacks against government workers and security forces.

The bus was traveling to a police academy in Jalalabad city when it was ripped apart in the explosion, Nangarhar province government spokesman Ahmad Zia Abdulzai said.

In the demonstration in Takhar province in the north, protesters fought with police and tried to assault a German military outpost in the city of Taloqan, the provincial capital, officials said, adding that some 50 were injured.

The protest was triggered by an overnight NATO raid on the outskirts of the city. The coalition said four insurgents died in the operation and that two others were detained.

Night raids targeting insurgents regularly stir up controversy in Afghanistan, where angry residents often charge the next day that international forces go after the wrong people or mistreat civilians as they search compounds. Success by NATO in reducing civilian casualties and agreements to conduct night raids alongside Afghan forces have not managed to stem the tide of accusations.

Adding to the confusion, it is often difficult to know who is a militant in insurgent-heavy areas, where entire villages are often allied with the Taliban or other groups.