China on Thursday took a more prominent role in efforts to contain Iran's nuclear drive and President Hu Jintao announced that he will go to a major anti-proliferation summit in Washington this month.
But while a top US official said China had agreed to "serious negotiations" on new UN sanctions, the Chinese government insisted it was working for a "peaceful resolution" of the nuclear standoff.
Iran sent its top nuclear negotiator to Beijing and described the talk of new international action as an empty threat.
The presence of Tehran's chief nuclear negotiator Saeed Jalili in Beijing highlighted China's role in the tense UN Security Council debate on Iran's uranium enrichment.
The United States and its allies suspect the programme is part of a drive to develop a nuclear bomb.
German Chancellor Angela Merkel held telephone talks with China's Premier Wen Jiabao on Iran, her office said.
But while Western nations are stepping up pressure for sanctions, China is sticking to its insistence on more talks.
"On the Iranian nuclear issue, China will continue to endeavour toward a peaceful resolution," Chinese foreign ministry spokesman Qin Gang told reporters.
"We have always and will continue to push for a peaceful settlement of this issue," Qin said, adding that the crisis should
be resolved by "diplomatic means".
Qin said Jalili would meet Foreign Minister Yang Jiechi and other Chinese officials.
Qin also announced that President Hu would attend US President Barack Obama's nuclear security summit in Washington on April 12-13.
The visit would be a chance for the two powers to ease tensions that have mounted in recent months as well as discuss Iran.
Obama said Tuesday he wants a fourth round of UN sanctions agreed upon within weeks.
China, one of five veto-wielding members of the Security Council, has repeatedly called for a negotiated settlement, rather than new punitive action.
But the US ambassador to the United Nations, Susan Rice, signalled a shift in China's attitude on Iran.
"China has agreed to sit down and begin serious negotiations here in New York," Rice told CNN on Wednesday.
"This is progress, but the negotiations have yet to begin in earnest," Rice said.
US Secretary of State Hillary Clinton predicted on Tuesday that the Security Council would reach a consensus on new sanctions.
"We see a growing awareness on the part of many countries including China as to the consequences of a nuclear-armed Iran to regional and global stability, to our oil supply," she said.
"We think that there will be a consensus reached as to the best way forward."
China has a close diplomatic and trade relationship with Iran, dominated by its imports of Iranian energy resources, and its position remains key to the future of the long-running standoff.
Russia has also been reluctant to agree new sanctions but has taken a harder line on Iran's nuclear programme in recent
The five permanent members of the Security Council -- Britain, China, France, Russia and the United States -- plus Germany have been involved in talks with Iran for months.
Oil-rich Iran insists its nuclear programme is peaceful and it has the right to nuclear technology.
The Tehran government on Thursday shrugged off talk of new sanctions.
"The nuclear programme of the Islamic republic is fully peaceful and the talk of sanctions is a threat that has been ineffective over the past 30 years," foreign ministry spokesman Ramin Mehmanparast said.
"We recommend that all countries accept the legal rights (of Iran) under the Non-Proliferation Treaty, instead of using wrong methods such as sanctions and pressure," Mehmanparast said, according to Mehr news agency.