A top US diplomat said Monday that China recognized the "danger" of Iran's nuclear program and dismissed suggestions that recent rows between Washington and Beijing had impeded cooperation.

China has been seen as the most hesitant member of the so-called "P5-plus-1" -- the five permanent UN Security Council members plus Germany that are negotiating with Iran -- over imposing further sanctions.

But Deputy Secretary of State James Steinberg said Chinese officials were willing to talk to him about cooperation on Iran when he visited Beijing earlier this month.

"We've had a recognition, I think, by our Chinese counterparts of the danger of the Iranian nuclear program and the fact that there does not seem to be a willingness on the Iranians to take the very generous offer that the P5-plus-1 made to them," Steinberg told reporters in Washington.

"Despite the very serious efforts, which we support, of the Chinese to encourage diplomacy on the part of the Iranians, they don't seem to be responsive," he said.

China last week joined the other five nations in a conference call to weigh proposed new UN sanctions against Iran.

Western powers suspect Iran is developing nuclear weapons, although the clerical regime says its uranium enrichment is for peaceful purposes.

Steinberg and Jeffrey Bader, President Barack Obama's top adviser on Asia, visited China in the wake of Beijing's protests over the US approval of arms sales to Taiwan and Obama's meeting with the Dalai Lama.

Steinberg said while he did not see "a direct linkage between these things," he was "very encouraged by the fact that, on issues of concern to us, we have seen some progress," citing Iran.

He said he explained US positions on Taiwan and Tibet and was "treated with great courtesy" in Beijing.