One of Ukraine's top fighter pilots has died after the NATO-donated F-16 he was in crashed while repelling a Russian missile attack.

It was the first reported loss of one of the aircraft since the US-made planes were delivered at the end of last month.

Pilot Oleksii "Moonfish" Mes shot down three cruise missiles and one strike UAV before he was killed in the crash, the Ukranian military said.

The Ukrainian Air Force paid tribute to the fallen airman and said he "heroically fought his last battle in the skies".

He and a fellow Ukrainian pilot, Andrii "Juice" Pilshchykov, made an early, public visit to the US in June 2022 to press politicians to send F-16 fighter jets to Ukraine. 

They both continued to serve as public faces for Ukraine's battle to secure its airspace amid Russia's invasion.

Juice was killed in an August 2023 accident.

"When I met with Ukraine pilots Juice and Moonfish I had a sick feeling they wouldn't make it through the war," former US congressman Adam Kingzinger posted on X.

"They fought like hell for Ukraine, and the F16."

The General Staff of the Ukranian Armed Forces said a special commission had been established to investigate the cause of the accident. 

"During the air battle, the F-16 aircraft demonstrated their high effectiveness, four cruise missiles were shot down by their onboard weapons," it said.

"At the time of approach, communication with one of the aircraft was lost. As it became known later, the plane became aware of the disaster, and the pilot took off.

"To find out the causes of the accident, a special commission has been established, which works in the area of ​​the plane's fall."

Ukraine's air force chief Mykola Oleshchuk said on Telegram that partners from the United States, where the F-16 is manufactured, were assisting with the investigation.

A US defence official told Reuters that the crash did not appear to be the result of Russian fire, and possible causes from pilot error to mechanical failure were still being investigated.

Earlier this month, Ukrainian President Volodymyr Zelenskyy confirmed the F-16s had started flying for operations within his country more than 29 months after Russia's invasion. 

"F-16s are in Ukraine. We did it. I am proud of our guys who are mastering these jets and have already started using them for our country," he said.

Ukraine had long lobbied for the use of the F-16s and Kyiv had hosted hundreds of meetings to obtain the fighter jets, which are equipped with a 20-millimetre cannon and can carry bombs, rockets and missiles.

In August 2023, US President Joe Biden granted authorisation for the US-built warplanes to be sent to Ukraine.

That came after months of pressure from Kyiv and internal debate in Washington, where officials feared the move could escalate tensions with the Kremlin.

Belgium, Denmark, the Netherlands and Norway — all NATO members — have committed to providing Ukraine with more than 60 of the planes.

That number is dwarfed by the Russian jet fighter fleet, which is about 10 times larger.

ABC/AP