Afghan protests over the burning of Qurans on a U.S. military base left 12 dead, making Friday the bloodiest day of demonstrations so far.

Despite a written apology by President Barack Obama aimed at calming the situation, demonstrations have raged across Afghanistan since news of the accidental burnings emerged on Tuesday.

At least 25 people have been killed in the protests so far, with NATO and Afghan forces struggling to contain the voilence.

Around 4000 protestors marched on the governor of Khost's compound, while in Nangarhar province thousands more chanted Death to America, according to the Associated Press.

The protests came after CBS News reported Thursday that an Afghan National Army soldier turned his gun on U.S. soldiers in eastern Afghanistan, killing two and wounding others.

A Norwegian soldier was also wounded Friday after a hand grenade was tossed into a coalition compound, the agency reported.

Angry mobs began to gather across Afghanistan on Tuesday after it emerged the Quran and other Islamic relics had been accidentally burned at Bagram airbase, north of Kabul, earlier in the week.

On Thursday President Barack Obama formerly apologized to Afghan President Hamid Karzai, expressing his deep regret for the reported incident, adding: The error was inadvertent. I assure you that we will take the appropriate steps to avoid any recurrence, to include holding accountable those responsible, Reuters reported.

We don't care about Obama's apology, said 25-year-old protestor Kamaluddin, according to AP.

 We have to protest to be responsible to our God. They are burning our Quran. An apology is not enough.

Elsewhere, Germany has ordered its troops away from a compound in Taloqan, northern Afghanistan.

A German Defense Ministry spokesman said the order to move the 50 soldiers came after protests in the area led to some of the men being injured.

In a statement, NATO's top commander Gen. John Allen said a full investigation had been launched into how the Qurans had ended up being incinerated.

The General asked for people to exercise patience and restraint as we continue to gather the facts.

Working together with the Afghan leadership is the only way for us to correct this major error and ensure that it never happens again, he said in a statement.