More than 1,000 Afghans in Kabul, Jalalabad and Herat clashed with police for a second day on Wednesday after NATO admitted to inadvertently burning copies of the Koran, the Muslim holy book.

Angry protesters hurled stones and shouted "Death to America, death to Obama, death to Karzai!"

On the outskirts of Kabul, shots were fired into the crowd, injuring several people.

"They are marching towards Kabul. Police are trying to stop them. We have sent more reinforcements to the area," Police spokesman Ashmat Estanakzai told the AFP news agency. Protesters attacked shops and brned cars along the way.

In the eastern city of Jalalabad, demonstrators praised the leader of the Afghan Taliban, screaming "Long live Mullah Omar!"

The US government and the commander of NATO-led forces in Afghanistan (ISAF), John Allen, apologized for "inappropriate treatment" of holy materials on Tuesday after local workers found charred copies of the Koran as they collected rubbish at Bagram Airbase.

"I have ordered an investigation into a report I received during the night that ISAF personnel at Bagram Airbase improperly disposed of a large number of Islamic religious materials which included Korans," Allen said.

NATO and the US government also said soldiers would receive training by March 3 on how to deal with religious materials in an appropriate manner.

The Korans had been taken from a detention center library at Bagram air base because they contained extremist messages. Inmates were suspected of using the holy book to pass secret messages to each other.

The incident comes only a month after a video recording surfaced of four US soldiers urinating on the bloodied corpses of three Taliban insurgents. The video showed one of the soldiers saying "Have a great day, buddy."

ng/dfm (Reuters, AFP, dpa)