Iran's supreme leader Ayatollah Ali Khamenei said Monday that the Islamic republic could boost uranium enrichment to 60 percent if needed, vowing to "not back down on the nuclear issue". "Iran's enrichment limit will not be 20 percent, and we will act to the point that is needed and the country requires," he was quoted as saying on his official website, adding that "we may bring enrichment to 60 percent" for nuclear propellants and other purposes. amh/kam/fz