Saturday, Ukrainian President Volodymyr Zelensky accused Iranian officials of lying about the delivery of drones to Moscow.
Iran has admitted for the first time that it sent drones to Russia but insists they were delivered before the Russian invasion of Ukraine.
In recent weeks, Ukraine and its Western allies have accused Russia of launching attacks using Iranian-made drones.
Tehran has repeatedly denied the allegations, but foreign minister Hossein Amir-Abdollahian was quoted on Saturday saying that Iran had sent drones to Russia before the invasion began in late February.
According to Iran's official news agency IRNA, Amir-Abdollahian said Iran supplied Russia with a limited number of drones before the Ukraine conflict.
However, he denied again that Iran had supplied Russia with missiles, calling the allegations "completely false."
"They decided to acknowledge that they supplied drones... But even in this admission of guilt, they lie "Zelensky said Saturday.
We shoot down at least ten Iranian drones per day, but the Iranian regime claims it has given very little, even before the beginning of a full-scale invasion.
Earlier, a spokesperson for the Ukrainian foreign ministry had cautioned Iran that "the consequences of complicity" with Moscow would be "greater than the benefit of Russia's support."
Britain and the European Union have sanctioned three Iranian generals and an arms company for allegedly selling drones to Russia.