A display featuring missiles and a portrait of Iranian Ayatollah Ali Khamenei is seen at Baharestan Square in Tehran, Sept. 27, 2017. Photo: Nazanin Tabatabaee Yazdi / TIMA via Reuters.

France lamented on Tuesday a US decision to end a sanctions waiver related to Iran’s Fordow nuclear facility, but also said it feared Tehran’s latest violations of a 2015 deal could lead to serious nuclear proliferation.

“We regret the decision of the United States, following Iran’s resumption of enrichment on the Fordow site, to terminate an exemption that would facilitate the conduct of civilian projects on this site,” Foreign Ministry spokeswoman Agnes von der Muhll told reporters in an online briefing.

The Trump administration, which last year pulled out of the Iran nuclear deal and re-imposed sanctions on Tehran, had until Monday let the work go forward at the Fordow fuel enrichment plant by issuing waivers to sanctions that bar non-US firms from dealing with the Atomic Energy Organization of Iran (AEOI).

The UN atomic watchdog and Iran itself said this month Tehran is again enriching uranium at the sensitive site, which Iran hid from UN non-proliferation inspectors until its exposure in 2009.

“France is extremely concerned by Iran’s non-compliance with its nuclear obligations, which may have serious consequences for proliferation,” von der Muhll said a day after Iran breached another limit in the nuclear deal by accumulating slightly more than 130 tonnes of heavy water.

“Iran’s resumption of enrichment activities at the Fordow site, with potentially serious proliferation consequences, is a new step that marks a regrettable acceleration of Iran’s withdrawal from the Vienna agreement.”

As the deal has slowly eroded, France, Britain and Germany have been torn between trying to save it and responding to Iran’s breaches.

French officials have in recent weeks stepped up efforts to try to bring Tehran and Washington back to the negotiating table, but with little sign of success.

They are trying to convince Iran to go back on a raft of decisions violating the accord and the United Nations to begin lifting some sanctions that have strangled Iran’s economy.

“France calls on Iran to comply fully with the agreement without delay,” von der Muhll said, adding that Paris was continuing its efforts to defuse tensions.