Iran and China agreed during talks in Beijing that sanctions “have lost their effectiveness”, chief Iranian nuclear negotiator Saeed Jalili said on Friday after meeting senior Chinese officials.

“In our talks with China it was agreed that tools such as sanctions have lost their effectiveness,” Jalili told a news conference, speaking via a Chinese translator.

Asked if China backs sanctions on Iran over its nuclear programme, he said: “It’s up to China to answer that.”

The United States said this week that six world powers, including China and Russia, are united in talks on a possible new round of sanctions against Iran over its nuclear programme.

Beijing has not commented directly on whether it is contemplating supporting further restrictions on Iran, but diplomats have dropped a phrase they were using earlier this year — that sanctions did not offer a “fundamental solution”.

Chinese Foreign Minister Yang Jiechi called for “flexibility” during talks with Jalili, who flew into Beijing on Thursday, the official Xinhua news agency reported.

Beijing, like Moscow, reluctantly backed three previous rounds of U.N. sanctions against Tehran for refusing to halt enrichment as demanded by five U.N. Security Council resolutions.

Iran rejects Western charges its atomic programme is aimed at developing bombs and says enrichment is a sovereign right.

Tehran insists its nuclear programme is intended only to peacefully generate electricity.

Diplomats say China has been slowly and reluctantly falling in line with other powers involved in the talks, though it wants any new steps against one of its major oil suppliers to be weak.

Jalili also said it was unacceptable to wield the threat of sanctions to press Tehran over a U.N.-backed nuclear fuel offer. That offer would have move Tehran’s low-enriched uranium stocks to Russia and France for processing into fuel for an ageing research reactor that produces medical isotopes.

“What is ridiculous is that if we don’t accept their conditions, they will impose sanctions on us,” said Jalili, speaking in Farsi, with a Chinese translator. “The logic of this remains unacceptable to the international community.”

Negotiations based on pressure will not work, he said.

Moscow, Western diplomats say, has become increasingly impatient with Iran’s lack of interest in the deal. Along with Beijing, it privately urged Iran to accept the offer as a goodwill gesture, but they did not receive any clear response.

That, diplomats say, is one of the reasons China agreed to join negotiations on a new U.N. sanctions resolution.

(Reporting by Chris Buckley; Writing by Emma Graham-Harrison; Editing by Benjamin Kang Lim and Jerry Norton)