Iran on Friday asked its citizens currently stationed in Ukraine to leave the country and advised others against traveling there as the protracted military showdown gets intense.
The Foreign Ministry said in a statement that all Iranian nationals presently in Ukraine should leave the war-ravaged country "for their own safety."
It also advised Iranian nationals to refrain from traveling to the country "due to military escalation and increasing insecurity."
The statement further asked Iranian nationals in Ukraine to "remain calm" and contact the country's embassy in Kyiv if needed.
The advisory comes amid a rapid escalation in the war, now in its eighth month, with Ukrainian forces making significant territorial advances in the regions recently annexed by Russia.
Tensions between Tehran and Kyiv have also heightened amid claims made by Ukrainian officials as well as the US and European officials about Iran supplying drones to Russia to be used in Ukraine.
On Thursday, White House National Security Council spokesman John Kirby alleged that Iran has deployed military experts in Russian-occupied Crimea to help launch drone attacks on Ukraine.
He said Iran was now "directly engaged on the ground" and through the supply of drones to Russia, adding that the US will "pursue all means" to "expose, deter and confront Iran's provision of these munitions against the Ukrainian people".
Ukrainian officials say that they identified the drones used by Russia on the Ukrainian cities on Monday as Iranian-made Shahed-136, known as "kamikaze drones."
However, both Iran and Russia have strongly refuted the reports, with Kremlin spokesman Dmitry Peskov on Tuesday saying they do not have any information on the matter.
Iran's Foreign Minister Hossein Amir-Abdollahian told EU's foreign policy chief Josep Borrell on Thursday that Tehran has "defense cooperation" with Russia but is opposed to the war in Ukraine.
He insisted that "it is not Tehran's policy" to send weapons and drones to be used against Ukraine, adding that Tehran is "trying to put an end to the war in Ukraine."
His remarks came shortly after the EU added three Iranian individuals and one entity to the list of sanctions for "undermining or threatening the territorial integrity, sovereignty and independence" of Ukraine.
The decision, it said in a statement, was the signal of the bloc's resolve to "respond swiftly and decisively to Iran's actions supporting Russian aggression against Ukraine."
The UK also announced sanctions against Iran on Thursday with Foreign Secretary James Cleverly calling Iran's alleged involvement in the Ukraine war "deplorable."
There have been reports that Iran promised Russia surface-to-surface missiles in addition to drones.
Some Western news outlets have even published photos of what they claim are remains of Iranian-made drones, Shahed-136 and Mohajer-6, allegedly used in Ukraine by Russian forces.
On Wednesday, the Iranian foreign minister told his Croatian counterpart, Gordan Grlic Radman, that Tehran is opposed to the war and arming any of the warring parties in Ukraine.
In a separate call with his Polish counterpart, Iran's President Ebrahim Raisi said his administration will use all its capacities, including diplomatic channels, to bring an end to the raging war.