US election 2012: Rick Santorum says Afghans should apologise for 'overreacting' over Koran burning

Abdul Rahim Wardak, the Afghan defence minister, telephoned Leon Panetta, the US Defence Secretary, and apologised for the killing of the Americans, the Pentagon said.

Mr Santorum's main Republican rival, Mitt Romney told Fox News Sunday that "with regards to the (Obama) apology, I think for a lot of people, it sticks in their throat.

"The idea that we are there, having lost thousands of individuals through casualty and death – we've made an enormous contribution to help the people there achieve freedom, and for us to be apologising at a time like this is something which is very difficult for the American people to countenance."

Mr Santorum said he does "commend the president for his commitment of troops" in the counter-insurgency mission in Afghanistan, while Mr Romney acknowledged the need for Americans to continue helping in the transition from US to Afghan control of security.

"We don't want to see Afghanistan once again return to a Taliban-dominated nation with al-Qaeda and other training camps," he said.

A third Republican presidential candidate, Newt Gingrich, made more strident denunciations of Mr Obama's apology, labelling him an appeaser and saying he was "deeply offended" that Mr Obama did not hold Mr Karzai responsible for the killings.

"There doesn't seem to be any request for an apology from Karzai," Mr Gingrich told Fox News on Saturday.

"And I frankly just think this one-sided process of apologising for America has gone too far," he said. "Churches get burned in Nigeria, there are no apologies. Churches get burned in Egypt, there are no apologies."