Major powers failed to settle all their differences over a second UN sanctions resolution against Iran for its nuclear activities, a senior U.S. official said on Saturday.

"There is still some work to be done on a few outstanding issues, but all parties remain committed to a second resolution in the near future," State Department spokesman Kurtis Cooper said in a statement after U.S. Under Secretary of State Nicholas Burns and his counterparts from China, Russia, France, Britain and Germany held discussions by phone.

"They had a good discussion in keeping with the positive atmosphere of their conversations" in recent days, Cooper said.

The major powers have been negotiating over a new Security Council resolution that will exert more diplomatic pressure on Iran's nuclear program.

"We've agreed on a couple of things: one, that we're going to go for a U.N. Security Council resolution; and two, that we are going to reaffirm to the Iranians that there is a negotiating track that is open to them," State Department spokesman Sean McCormack said early this week.

The UN Security Council passed a resolution on Dec. 23, 2006 demanding Iran to suspend uranium enrichment in 60 days. However, Iran has failed to do so and claimed its nuclear program is for civilian purposes only.

The United States has accused Iran of trying to develop nuclear weapons under the cover of a civilian program, a charge that Iran has denied.

Source: Xinhua