The United States on Monday said time was running out for Iran to address the growing concerns of the international community about its nuclear programme, as the Islamic republic approved plans to build 10 new uranium enrichment facilities in defiance of UN demands.

"If true, this would be yet another serious violation of Iran's clear obligations under multiple UN security council resolutions, and another example of Iran choosing to isolate itself," the White House Press Secretary, Robert Gibbs, said in a statement here.