President Volodymyr Zelensky says Russia has launched more than 30 drone attacks on Ukraine in just two days.
He added that in total, Moscow had also carried out some 4,500 missile strikes and over 8,000 air raids.
Speaking from Kyiv and standing beside what appeared to be a downed Iranian Shahed drone, Mr Zelensky pledged to “clip the wings” of Moscow’s air power.
Western officials believe Iran has supplied a large number of drones to Russia, but Moscow and Tehran deny it.
It comes as US Secretary of State Antony Blinken called Russia’s aggressive use of drones “appalling”.
The top US diplomat accused Russian commanders of using the devices to “kill Ukrainian civilians and destroy the infrastructure they rely on for electricity, for water, for heat” during a visit to the Canadian capital Ottawa.
“Canada and the United States will keep working with our allies and partners to expose, to deter, and to counter Iran’s provision of these weapons,” Mr Blinken said.
In recent weeks, Russian attacks have targeted Ukraine’s civilian infrastructure, damaging the country’s electricity and water supply just as temperatures begin to drop.
Western countries say Iran is supplying its domestically developed drones to Moscow and that Iranian military experts are on the ground in Russian-occupied Crimea to provide technical support to pilots.
Kyiv has identified the drones used in some attacks on its infrastructure as Iranian Shahed-136 drones. They are known as “kamikaze” drones because they are destroyed in the attack – named after the Japanese fighter pilots who flew suicide missions in World War Two.
Ukraine says around 400 drones have already been used by Russia, from a total order of roughly 2,000 weapons.
But Tehran has repeatedly denied that it has struck any arms deal with the Kremlin, and Moscow also denies using Iranian drones.
On Wednesday, Iran’s Foreign Minister Hossein Amir-Abdollahian called the accusations “baseless” and urged Ukraine to “present any evidence supporting the accusations”.
“If… it becomes clear to us that Russia has used Iranian drones in the war against Ukraine, we will definitely not be indifferent about this issue,” he added.
Israel, a rival state in the region to Tehran, has also criticized Iran for the purported exports. President Isaac Herzog denounced the actions of the regime while speaking with US President Joe Biden on Thursday at the White House.
“It gives you a picture of what Iran is all about,” Mr. Herzog said, “following its activities in killing its own citizens, in working endlessly toward nuclear weapons, endangering the entire world and the region—and now killing innocent civilians in Ukraine.”
He had promised to provide Mr. Biden with “proof” that Iran was providing the weapons before the visit.
According to the Associated Press, US officials have stated that they will provide Ukraine with an additional $275 million (£237 million) in military aid.
The aid is anticipated to be used to restock ammunition for Ukrainian artillery systems, including the highly effective HIMARS launchers.
Combat has slowed recently on the ground as a much-anticipated Ukrainian advance on the southern city of Kherson was stalled by bad weather.