A state-of-the-art F-16 jet worth an eye-watering £60million, potentially loaded with UK-supplied missiles, has been deployed by Ukraine for the first time, according to pictures circulated by an Odesa-based news outlet.

And so alarmed is Vladimir Putin by the development that he is thought to be offering six-figure rewards for Russian personnel who successfully manage to destroy one.

The image, supplied by Dumska, coincides with reports that Kyiv has received the first batch of fourth-generation US-built warplanes after two years of delays.

Half a dozen supplied by the Netherlands are thought to be in the country, with more from Denmark to follow soon, with further aircraft coming from Belgium and Norway.

Ukraine hopes that the F-16s - long demanded by Volodymyr Zelensky - will strengthen his defences despite their small number.

Oleksiy Sukhoi, a military columnist for Dumskal, said: "Western partners delivered the planes, as agreed, at the end of July.

“This is undoubtedly a big step forward.”

Dumska said its photograph - branded with its logo - was an “exclusive”, adding: “The first F-16 fighters have already been spotted in the sky over Ukraine”.

Russia is said to be offering a £135,000 reward for the downing or destruction of each F-16.

Putin insists the warplanes would not change the situation on the battlefield, but will simply lead to a prolongation of the war.

He also claimed that they would burn like other much-touted Western military equipment.

It is unclear whether the F-16s can be immediately used in the war or whether further training is involved inside Ukraine.

Confirming the arrival of the aircraft, Lithuanian Foreign Minister Gabrielius Landsbergis said: “F-16s in Ukraine.

“Another impossible thing turned out to be totally possible.”

A US official, speaking on the condition of anonymity, said the delivery had been complete, although Ukraine has not formally commented.

The initial use of the F-16s is expected to be defensive.

The F-16s, costing £63 million each, will likely have three core missions, says Federico Borsari of the Center for European Policy Analysis in Washington.

They will seek to intercept Russian missiles and drones that have relentlessly bombarded Ukraine; suppress enemy air defence systems; and strike Russian troop positions and ammunition depots with air-to-ground missiles.

Mr Borsari said: “They will be able to affect some of the dynamics of the war.”

A lot of information about the F-16 deployment is classified, including what Western governments allow them to hit and what weapons they will send with the aircraft.

The F-16s could carry United Kingdom-supplied Storm Shadow air-launched cruise missiles with a range of more than 155 miles, potentially striking targets inside Russia.

They might also get long-range air-to-air missiles that would threaten Russian bombers and fighter jets. The plane’s advanced radars will allow Ukrainian pilots to pinpoint targets further away than they can in their MiG-29s, Su-27s and Su-24s.