The European Union is expected to draw up a list of sanctions against Iran in retaliation to their sale of deadly drones to Russia to use in its war against Ukraine.

Officials and diplomats said Wednesday that they have gathered sufficient evidence proving Iran has indeed been supplying Russia with cheap weapons capable of precise explosive attacks.

An E.U. official said the sanctions could be finalized as soon as Thursday, and that the group is working up a list of Iranian entities and individuals to penalize.

The drones that Iran is supplying to Russia are known as Shahed-136s, or kamikaze drones, as they do not carry weapons, instead flying into their target directly.

As of this week, Iran continued to deny their suppliance of the deadly weapons to Russia. In August, the Washington Post reported that Russian cargo planes received the first shipment of Iranian-made combat drones for use against Ukraine.

These latest sanctions will come the same week E.U. foreign ministers sanctioned Iran's morality police, as well as 11 other officials, over the crackdowns battering anti-government protests.

Some within the E.U. have expressed criticism over the pace with which the group addressed Iran's military sales with Russia.

Lithuanian Foreign Minister Gabrielius Landsbergis tweeted his displeasure with the initial E.U. response to Iran.

The shocking drone attacks that took place in the Ukrainian capital on Monday seemed to spur E.U. officials to rally around the issue.

Russia's reliance on drones has grown in large part due to Ukraine's Western-reinforced air defenses, which have made manned Russian warplanes difficult to operate.