The United States urged yesterday the United Nations Security Council to take "meaningful steps" to address the alleged threat posed by Iran's nuclear issue.

"It's time for the Security Council to act and take additional steps on the diplomatic front," White House spokesman Scott McClellan told reporters.

"We are making it very clear that there needs to be meaningful steps taken at the Security Council to address the threat posed bythe regime's continued defiance."

U.S. Under Secretary of State Nicholas Burns is in Moscow having meetings with his counterparts of a number of countries to discuss ways to settle Iran's nuclear issues, McClellan said.

It was reported that senior diplomats from Britain, China, France, Germany, Russia and the United States met in Moscow Tuesday to discuss ways to keep Iran's nuclear program in check.

Iran announced last week that Iran had successfully produced 3.5 percent enriched uranium, saying the success in producing low-grade enriched uranium would pave the way for the Islamic republicto start industrial-scale production.

The United States has accused Iran of trying to develop nuclearweapons under the cover of civilian nuclear programs. Iran rejectsthe U.S. charges, and insists its nuclear programs aims only to generate electricity.

The U.S. said it wanted the UN Security Council to be ready to take strong diplomatic action, including so-called targeted measures such as a freeze on assets and visa curbs.