Iran's Foreign Ministry has advised its citizens to refrain from traveling to Ukraine "due to the escalation of military conflicts and the increase in insecurity in Ukraine."
The ministry said in a statement on October 21 that Iranians in Ukraine are advised to leave the country "in order to save their lives and safety."
Since Russia's unprovoked invasion of Ukraine on February 24, the two sides have fought pitched battles in many region's of the country, especially in the east and south.
In recent weeks, Russia has launched a barrage of missiles and kamikaze drone attacks on cities across Ukraine, including the capital, Kyiv.
The United States said on October 20 that Iran was helping Russia operate the drones.
The White House said Iranians had been on the ground in Crimea helping Russians target Ukraine with Iranian drones.
The Iranian statement did not mention the issue, but in a statement on October 21 outlining a phone call between Foreign Minister Hossein Amir-Abdollahian and the European Union's top diplomat, Josep Borrell, Tehran reiterated earlier comments that it "vehemently rejects claims that it has given Russia drones for use in the conflict in Ukraine."
Russia seized Crimea from Ukraine in 2014.