Iran’s planned expansion of its nuclear program is “deeply worrying,” European powers said Monday, warning recent actions by the Islamic Republic could jeopardize shared efforts to salvage the landmark nuclear deal.

The so-called E3 grouping of France, Germany and the United Kingdom denounced a recent announcement from Tehran to the UN’s atomic watchdog that it planned to install hundreds more advanced centrifuges at its underground Natanz nuclear facility.

Since President Donald Trump unilaterally withdrew the United States from the Joint Comprehensive Plan of Action (JCPOA) in 2018 and reimposed harsh economic sanctions, Iran has steadily enriched uranium in violation of the agreement. The deal’s other signatories — Russia, China, France, the United Kingdom and the European Union — remain part of the accord and have called on Iran to return to full compliance. 

Last week, Iran’s hard-line parliament voted to increase uranium enrichment and ban UN inspectors from accessing Iran's nuclear facilities if sanctions relief is not forthcoming by early February. The legislation, which came in apparent retaliation for a suspected Israeli assassination of one of Iran’s top nuclear scientists, still requires President Hassan Rouhani’s signature to become law.