"I was particularly pleased of the fact that we made progress in our deliberations with the Chinese government," said U.S. Undersecretary of State Nicholas Burns, the chief American participant in Saturday's closed door, high-level talks in Paris.
The clamor for new sanctions - led by the United States, Britain and France - mounted after Friday's collapse of an 18-month EU effort to persuade Iran to stop uranium enrichment.
China, a veto-wielding member of the U.N. Security Council, together with Russia, had been reluctant to support a third set of sanctions.
"We were able, with the Chinese government, to focus on a number of areas where we would agree to sanctions ... It was a step forward for us," Burns told reporters in Singapore where he met with officials to discuss bilateral and regional issues.
Burns said the Russian government still had to be consulted on the sanctions resolution as the Russian official scheduled to attend the talks, Deputy Foreign Minister Sergei Kislyak, was stuck in Canada because of snow.
"Now if we can bring the Russians on board, we'll have the makings of a third Security Council resolution and that would be very welcome news indeed," Burns said.
A French diplomat had said following the talks that a compromise text on a new resolution would be circulated among the six countries involved in negotiations - the United States, Britain, France, Russia, China and Germany - next week.
The diplomat, who spoke on condition of anonymity due to the sensitivity of the talks, said he was "relatively optimistic" about having a resolution in the coming weeks.