Afghans protest Koran burning

Angry demonstrators march towards the palace of Afghan President Hamid Karzai in Kabul.

They are protesting against the burning of copies of the Koran at a NATO base.

Riot police and soldiers are put on high alert as protests enter the fourth day.

(SOUNDBITE) (Pashto) PROTESTERS, ZARYALI KHAN, SAYING:

"The infidels burnt our Koran, the book that we believe. We came here to tell Karzai that if this is an Islamic republic country, why are the infidels insulting Islam? Why do they want to root out Islam value instead of bringing democracy? We don't want them to insult our religion, our book and our messenger."

U.S. President Barack Obama has sent a letter to Karzai apologizing for the unintentional burning of the Korans at NATO's main Bagram air base, north of Kabul.

Afghan labourers found charred copies while collecting rubbish.

Afghanistan wants NATO to put those responsible on public trial.

On Friday alone, twelve people were killed during protests across the country, bringing the total number of casualties to 23 which included 2 American soldiers.

Most westerners have been confined to their heavily fortified compounds, including the U.S. embassy complex.

Sarah Wali, Reuters.