Media playback is unsupported on your device Media caption The protests over the Koran burning appear to be spreading

Afghan President Hamid Karzai has called on Afghans "not to resort to violence" over the burning of copies of the Koran at a US airbase near Kabul.

"Afghan security forces should not use violence... and protect civilian lives and property," Mr Karzai added in a statement.

Seven people have died and dozens left injured in protests over the burning.

US officials apologised on Tuesday after Korans were "inadvertently" put in an incinerator at Bagram airbase.

Officials at Bagram reportedly believed Taliban prisoners were using the books to pass messages to each other.

The charred pages of the volumes were found by local labourers.

Pro-Taliban slogans

One person was killed in protests in Kabul, one in the eastern city of Jalalabad and at least four in Parwan province. Another death was reported in the eastern province of Logar.

Protesters in Kabul shouted, "Death to America!" and threw stones at Camp Phoenix, the main US base in the city.

At the scene There were several demonstrations across Nangarhar province and at least two in the main city of Jalalabad. The first happened at the university. Students were angry, chanting slogans against US troops. They were determined but not violent. A second demonstration elsewhere in the city turned ugly. I arrived as injured protesters were being taken to hospital in ambulances and private cars. People said the US apology was not enough. Oil tankers had been set ablaze. The protesters' message was that Afghans respect the religious beliefs of troops inside Afghanistan, so why have they failed to respect Islam and the Koran?

Riot police used water cannon to disperse protesters, some of whom were blocking the road leading to Jalalabad, one of the main trade routes into the capital.

Witnesses said security guards were firing into the air. There were also reports of people chanting pro-Taliban slogans.

Four deaths were confirmed in the Shinwari district of Parwan province, north of Kabul. There were also peaceful protests in the eastern province of Kunar.

In Jalalabad, protesters burned an effigy of US President Barack Obama, and BBC Afghan reporter Babrak Miakhel said oil tankers had been set on fire.

A doctor told the BBC one person had been killed and 10 injured.

One protester in Kabul, 18-year-old Ajmal, told Reuters news agency: "When the Americans insult us to this degree, we will join the insurgents."

The US embassy in Kabul is on lockdown and all travel is suspended.

The Taliban called on Afghan police and soldiers to redeem themselves by turning their guns away from protesters and towards Nato-led troops.

In a statement after an emergency debate, Afghan MPs condemned what had happened.

They also called for punishment of those responsible and asked the Afghan government to send its own delegation to Bagram to establish exactly what happened and why.

Isaf investigation

US Defence Secretary Leon Panetta said he and the top commander of US and Nato forces in Afghanistan, Gen John Allen, had apologised to the Afghan people "and disapprove of such conduct in the strongest possible terms".

After previous incidents, many Afghans find it hard to understand how US forces could have allowed the Koran to have been burned, says the BBC's Andrew North, in Kabul.

Media playback is unsupported on your device Media caption Isaf spokesman Brig Gen Carsten Jacobson says the incident was an unfortunate mistake

Afghanistan is a very religious country, he adds, but also one where many people are illiterate and susceptible to attempts to whip up anger.

Muslims consider the Koran the literal word of God and treat each book with deep reverence.

The Nato-led Isaf force is now investigating the incident, a spokesman told the BBC.

"It was the local workers who discovered the nature of the material and therefore stopped worse things from happening," said Brig Gen Carsten Jacobson.

Last year, at least 24 people died in protests across Afghanistan after a hardline US pastor burned a Koran in Florida.