Iran said members of the Non-Aligned Movement should establish a system that a government spokesman said would counter a Western monopoly on power. Tehran this week hosted delegates from the 120-member NAM. Participants included heads of state and U.N. Secretary-General Ban Ki-moon. Iranian Foreign Ministry spokesman Ramin Mehmanparast told Iran\'s state-funded broadcaster Press TV that NAM advocated an international system not managed exclusively by Western powers. \"We (the NAM members) call for establishment of justice in the international relations and abolition of the monopoly on the global management system by a number of Western countries who have put their interests before everything and trample the other countries\' rights,\" he said. The conference comes amid growing concerns over Iran\'s nuclear program. White House spokesman Jay Carney said the window of opportunity for Iran to address international concerns wouldn\'t remain open forever. U.S. President Barack Obama, he said, \"has made clear that all options are on the table\" to prevent Iran from acquiring a nuclear weapon. A report from the International Atomic Energy Agency states Iran has doubled the number of installed centrifuges and cleaned suspected nuclear sites to the point that it would \"significantly hamper\" the work of inspectors, The New York Times reports. The IAEA had said it suspects there may be military aspects to parts of Iran\'s nuclear program. Iranian Supreme Leader Ali Khamenei told NAM delegates Thursday that Tehran considers nuclear, chemical and similar weapons \"a great and unforgivable sin,\" however.