The foreign ministers of Britain, France and Germany on Friday said they opposed lifting a UN arms embargo on Iran this year, after the UN's nuclear watchdog passed a resolution critical of Tehran.
"We believe that the planned lifting of the UN conventional arms embargo established by Resolution 2231 next October would have major implications for regional security and stability," the ministers said in a joint statement.
The statement by the three key European powers on Iran will be a blow to Tehran, which had urged a lifting of the embargo despite US pressure for it to remain in place.
The ban on selling weapons -- such as battle tanks, combat aircraft, warships and missiles or missile systems -- to Iran had been set to be progressively eased from October.
Iranian President Hassan Rouhani earlier this month urged UN Security Council members to oppose a US "conspiracy" to extend the arms embargo.
The three powers said they plan to address the arms embargo issue "in close coordination" with UN Security Council permanent members Russia and China.
The board of governors at the International Atomic Energy Agency (IAEA) had passed a resolution on Friday urging Tehran to provide inspectors with access to two sites to clarify whether undeclared nuclear activity took place there in the early 2000s.
It was the first such resolution since 2012 and came against a background of tension over the Iranian nuclear programme, with Iran's position causing increasing exasperation in Europe.
"Since 2019, Iran has taken nuclear measures contrary to its commitments" under the 2015 deal on its nuclear programme with world powers, the ministers' statement said.
It added that Iran "has denied the access requested by the agency for many months" to the sites.
But the powers insisted they remained committed to the 2015 nuclear deal, which analysts believe has been greatly undermined by the withdrawal of the United States in 2018.
They said sanctions should not be reimposed and that they opposed the "maximum" pressure policy against Iran of the administration of US President Donald Trump.
"We firmly believe that any unilateral attempt to trigger UN sanctions snapback would have serious adverse consequences" in the UN Security Council.
"We remain committed... (to the nuclear deal) and, in order to preserve it, urge Iran to reverse all measures inconsistent with the agreement and return to full compliance without delay," said the statement.