Obama draws criticism for apology on Koran

US President Barack Obama is drawing criticism from Republican presidential hopefuls for apologizing for the burning of Muslim holy books at a US military base in Afghanistan.

Obama sent a letter of apology to Afghan President Hamid Karzai last week, saying measures will be taken to prevent such incidents from happening again.

Republican presidential hopeful Rick Santorum said on ABC television on Sunday that Obama should not have apologized for an act that he says was not intentional.

Former Massachusetts governor Mitt Romney said in a separate program that the US has made an enormous contribution in Afghanistan to help people achieve freedom, and that Obama's apology is unacceptable.

The burning of the Korans by US soldiers has triggered a wave of angry protests in Afghanistan.

Senior Afghan officials including the defense minister have called off a trip to Washington this week where they were going to discuss the timing of the withdrawal for NATO troops. They say they will instead stay home to deal with the demonstrations.