The US and three European powers on Thursday (February 18) warned Iran on the danger of limiting UN nuclear agency inspections, and asked Tehran to return to full compliance with the 2015 nuclear deal, the Joint Comprehensive Plan of Action (JCPOA).
The US, France, Germany and the UK said they were "united in underlining the dangerous nature of a decision to limit International Atomic Energy Agency (IAEA) access" ahead of a February 21 deadline set by Iran's Majles.
Iran has warned it would restrict some IAEA inspections starting February 21 if the US does not lift sanctions imposed since 2018.
Their statement urged "Iran to consider the consequences of such grave action, particularly at this time of renewed diplomatic opportunity", adding that they all shared the aim of Iran returning to "full compliance" with the accord.
The US has said it is prepared to rejoin the deal and start lifting sanctions if Iran -- whose economy is on the brink of bankruptcy -- returns to full compliance.
The Western powers have also expressed their concern over Iran's recent actions to produce both 20% enriched uranium and uranium metal, which is considered a key step in the development of a nuclear weapon.
On Thursday, the new US administration reversed two largely symbolic steps against Tehran.
US President Joe Biden has insisted he will not remove sanctions until Iran returns to compliance, but in a letter to the United Nations, the United States said it no longer believed that the UN had "snapped back" sanctions on Iran.
The United States also removed curbs on Iranian diplomats in New York.
Later that day, the US State Department said Washington "would accept an invitation" from the EU to attend a meeting of the nuclear deal's original signatories "to discuss a diplomatic way forward on Iran's nuclear programme".
Senior EU diplomat Enrique Mora tweeted he was "ready to invite" all parties to talks, saying this was a "critical moment" for the deal.