It was unclear if the talks occurred before or after the United States announced its intention to join talks on Iran's nuclear program, provided Tehran stopped enriching uranium, in a major policy shift.

The announcement signalled an apparent deal to win Russian and Chinese backing for UN sanctions against Tehran if needed.

"Their major topic was how to properly handle the Iran nuclear issue through diplomatic means," Xinhua quoted a foreign ministry statement as saying.

The statement did not elaborate on the content of the discussion.

As world powers geared to meet Thursday in Vienna to mull the standoff with Iran, Washington said it was ready to enter the European-led negotiations if Tehran suspended uranium enrichment activities.

A senior US official, who asked not to be named, linked the move to what he called an agreement by Russia and China to ease their categorical opposition to UN sanctions on Iran.