Ukraine's foreign ministry says it has summoned a senior Iranian diplomat to warn of "devastating and irreparable consequences" for bilateral relations if reports that Tehran had supplied Russia with ballistic missiles were correct.
A senior Iranian official denied the reports earlier on Monday, describing them as "psychological warfare". A European Union spokesperson described the information as "credible".
CNN and the Wall Street Journal reported last week, citing unidentified sources, that Iran had transferred short-range ballistic missiles to Russia, as Moscow continues to wage war in Ukraine more than two and a half years after its 2022 invasion.
The Ukrainian foreign ministry said on Telegram it had summoned Iran's charge d'affaires, Shahriar Amouzegar, and warned him in "harsh form" about the consequences for relations if delivery of the missiles was confirmed.
Earlier, Brigadier Fazlollah Nozari, a senior Iranian Revolutionary Guards commander, was quoted by the Iranian Labour News Agency as saying: "No missile was sent to Russia and this claim is a kind of psychological warfare."
"Iran does not support any of the parties to the Ukraine-Russia conflict," Nozari said.
Western and Ukrainian officials have dismissed such denials in the past, saying there is overwhelming evidence that Iran has supplied items such as Shahed drones to Russia.
EU foreign affairs spokesperson Peter Stano said in an email: "We are aware of the credible information provided by allies on the delivery of Iranian ballistic missiles to Russia."
He said that if confirmed, "this delivery would represent a substantive material escalation in Iran's support for Russia's illegal war of aggression against Ukraine".
EU leaders had previously made clear they would "respond swiftly and in coordination with international partners, including with new and significant restrictive measures against Iran" to such a step, Stano added.
Another European official, speaking on condition of anonymity, said the US had shared information on the reported transfer with allies and was likely to make it public soon.
Kremlin spokesman Dmitry Peskov said he had seen the report but that not all such reports were correct.
"Iran is our important partner, we are developing our trade and economic relations, we are developing our cooperation and dialogue in all possible areas, including the most sensitive ones," Peskov told reporters.
Ukraine said last week that deepening military cooperation between Tehran and Moscow was a threat to Ukraine, Europe and the Middle East, and called on the international community to increase pressure on Iran and Russia.
Any Iranian transfer of ballistic missiles to Russia would mark a sharp escalation in the Ukraine war, the United States said on Friday.
That language was echoed on Monday by a NATO spokesperson, who said the Western military alliance was aware of the media reports but would not be drawn on whether they were accurate.
"As Allies have stated previously, any transfer of ballistic missiles and related technology by Iran to Russia would represent a substantial escalation," the spokesperson said.
