China's ambassador to the UN says a new US intelligence report on Iran's nuclear programme raises questions about the need for new sanctions.
Mr Wang was asked if the report made more sanctions less likely
The ambassador, Wang Guangya, said the UN Security Council would have to consider the new information because "now things have changed".
A US intelligence report released on Monday said Iran halted a nuclear weapons programme in 2003.
The US and its European allies are still pushing for sanctions on Iran.
Mr Wang was asked whether the new National Intelligence Estimate (NIE) on Iran made the prospect of a third round of UN sanctions against Iran less likely.
"I think the council members will have to consider that, because I think we all start from the presumption that now things have changed," he said.
He said diplomats would have to think about the implications of the report for Security Council action.
China has reluctantly supported two rounds of UN sanctions against Iran over its refusal to stop enriching uranium.
The assent of China - and Russia - is crucial if the UN is to pass a third round of sanctions. Both countries wield a veto over Security Council decisions.
The text of a draft resolution could be circulated by the end of the week, says the BBC's Laura Trevelyan at the UN.
The French and British foreign ministers have said pressure should be maintained on Iran over its refusal to stop enriching uranium - a process which can have both civilian and military purposes.
US President George W Bush said on Tuesday that Iran remained a threat to the world despite the report's suggestion that Iran might not be building nuclear weapons.
He said Monday's report was a "warning signal" and his view that a nuclear Iran would be a danger "hasn't changed".
US Secretary of State Condoleezza Rice has telephoned the foreign ministers of China, France, Germany and the EU's foreign policy chief Javier Solana to discuss Iran's nuclear programme.
She said it would be a "big mistake" to ease the pressure on Tehran.
The NIE said with "high confidence" that it believed Iran had halted its nuclear weapons programme in 2003, but that it was continuing to enrich uranium.
It said Tehran could have enough highly enriched uranium to build a bomb within three to eight years.
The declassified summary of the combined assessment of the US's 16 intelligence agencies said Iran was keeping its options open on developing nuclear weapons.
Mr Bush said the report had not changed his opinion
Tehran denies accusations that it is developing nuclear weapons and says its nuclear programme is for civilian purposes only.
Iran has welcomed the report, with Iranian television hailing it as a "victory".
The country's chief nuclear negotiator, Saeed Jalili said: "The agency's report proved that many of the allegations [against Iran] were baseless".
The UN's nuclear watchdog, the International Atomic Energy Agency (IAEA), said in a report last month that Iran was making "good progress" in answering questions about its programme.
But IAEA head Mohamed ElBaradei has called on Iran to clarify some aspects of its past and present nuclear activities.