Afghan President Hamid Karzai on Sunday reiterated his call for calm and called upon Afghan people to remain peaceful following days of angry protests over Quran burning by U.S. forces that left dozens killed and hundreds injured in parts of the country."Now it is the time to return to calm and stay peaceful, not to allow the enemies of peace and stability to exploit the situation and damage public and private properties,” the Afghan president told reporters at a press conference in his fortified palace.Karzai condemned in strongest terms the alleged burning of Muslim holy book Quran by U.S. troops and demanded punishment for those behind the incident.The Afghan leader once again instructs the security forces to exercise patience and self-restraint toward the emotional protestors and ensure their safety and security."We are sharing the grief and pain with the mourning families who lost their love ones during the recent incidents in the country,” Karzai said, adding "the government is not indifferent with the people in the issue of desecration of holy books, but has been following with the American authorities on the need to bring to justice the perpetrators of the crime.”The protests erupted Tuesday when copies of Quran were allegedly burned outside the U.S.-run Bagram airbase, 50 km north of Afghan capital Kabul.The main U.S. military base in Afghanistan lies in Bagram where hundreds of suspected Taliban and al-Qaida operatives have been held.