China said on Friday it opposed a move by European powers to reintroduce sanctions on Iran over its nuclear programme, warning that such steps would damage trust and undermine ongoing diplomatic efforts.

Foreign ministers from Britain, France, and Germany—known as the E3—told the United Nations this week that they were prepared to reinstate sanctions by the end of August if Tehran failed to address concerns over its nuclear activities.

Beijing, however, criticised the threat, with foreign ministry spokesman Lin Jian insisting sanctions would not be “conducive to the diplomatic effort for the early resumption of talks”. He added that the move “does not help parties build trust.”

European penalties on Iran were lifted under the 2015 nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA), in exchange for restrictions on Tehran’s nuclear development. But that agreement unravelled after then-US President Donald Trump withdrew from it in 2018 and reimposed Washington’s own sanctions.

The E3 letter to UN Secretary-General Antonio Guterres and the Security Council accused Iran of multiple breaches, including stockpiling uranium at more than 40 times the limit set by the JCPOA. The ministers stressed they remained committed to diplomacy but warned they would use the deal’s “snapback mechanism” to restore sanctions if necessary.

Iran responded by saying it was working with China and Russia to block any reinstatement of penalties. Foreign Minister Abbas Araghchi argued that Europe had no legal authority to restore sanctions, calling the consequences “exaggerated” but warning that Tehran had “tools to respond” if the measures were revived.

The JCPOA is set to expire in October, and the latest exchange of warnings highlights the fragile state of the deal. The situation has been further inflamed by June’s conflict between Israel and Iran, which included a US airstrike amid efforts to curb Tehran’s nuclear capacity.

China urged the Security Council to focus on facilitating dialogue. “Any moves taken now should help reach new agreements in talks, instead of the opposite,” Lin said.