President Barack Obama was yesterday forced to apologise over the burning of Korans at a US airbase in Afghanistan, where three days of protests have killed 14 people, including two American soldiers.

Violent anti-US protests have seen furious Afghans attack French, Norwegian and US bases, shouting “death to America” after the Taliban exhorted their countrymen to kill foreign troops to avenge the incident at a US-run base.

Afghanistan is a deeply religious country where slights against Islam have frequently provoked violent protests, and many Afghans are incensed at the discovery of charred Korans at the US-run Bagram airbase north of Kabul.

In a letter of apology to Afghan President Hamid Karzai, Mr Obama expressed “deep regret” over the incident that he said was unintentional and pledged that those responsible would be held accountable, Kabul said.

“I extend to you and the Afghan people my sincere apologies,” Mr Obama wrote in the letter presented to Mr Karzai by United States ambassador Ryan Crocker.