The United States says it will go on pressuring Iran over its controversial nuclear issue and continue its work within the Iran Six mediators format, a U.S. Department of State official said.

"We are going to put pressure on Iran. We're going to show our resolve. We're going to show our commitment to the parties in the Middle East peace process. That's what the American people expect us to do," Assistant Secretary Philip Crowley told a daily press briefing.

Earlier in the month, the Iran Six discussed a possible new UN Security Council resolution that imposes further sanctions against Tehran over its nuclear program. The six countries, including the United States, France, Britain, Germany, China and Russia, comprise a group of international mediators negotiating with Iran on its nuclear program.

"We have a 30-year history with Iran. On the one hand, we're disappointed that Iran has not engaged meaningfully. On the other hand, we continue to work with our partners in the P-5+1 process and others on an effective sanctions package that will have an impact on this situation," he added.

Western powers suspect that Iran's nuclear program is aimed at making weapons, while Tehran claims it is pursuing nuclear technology for its civilian energy needs.

Under a plan drawn up by the IAEA last October, Iran was to ship out its low-enriched uranium to Russia, where it would be enriched and then sent to France to be made into fuel rods and returned to the Islamic Republic for use in its research reactor in Tehran.

The proposal was approved by the six international mediators on Iran's nuclear program but then rejected by Tehran, which suggested it could consider a simultaneous swap of its low-enriched uranium for 20%-enriched uranium, but that the exchange would have to take place on its own territory.

MOSCOW, March 17 (RIA Novosti)