The comments came after Ukrainian President Volodymyr Zelensky visited London on Wednesday, before moving on to Paris and Brussels, to urge allies to supply combat aircraft for use against Russian invaders.

Britain has said it will start training Ukrainian fighter pilots, and consider sending jets in the "long-term", although the United States and other NATO allies remain wary of getting more embroiled in the conflict.

"We are aware of potential escalatory risks," Sunak's spokesman told reporters about the broader policy of arming Kyiv, when asked about concerns in some European capitals about antagonising Moscow.

"But throughout we have been confident the approach we are taking is the best and quickest way to help Ukraine end this war, which is obviously in everyone's interest," he said.

Britain currently has two fighter jets on deployment: the cutting-edge F35B, and the older Eurofighter Typhoon, which was produced in collaboration with Germany, Italy and Spain.

Speaking on a visit to Rome, Defence Secretary Ben Wallace said he was already sending UK-made Challenger 2 tanks to Ukraine, but would need clearance from the other European nations to send any Typhoons.

"But also Britain hasn't said it is necessarily going to send fighter jets to Ukraine," he stressed.

"What it's said is we're going to start training to improve the resilience of Ukraine, probably post-conflict."

Sunak's spokesman said London would keep discussing "provision of capabilities" with allies, noting "every action we take will obviously have an eye to potential risks of escalation".

But he argued Russia itself was "escalating everything" in its ongoing attacks on Ukraine and occupation of swaths of its territory.

As the one-year anniversary of Russia's invasion looms and Ukraine braces for a fresh Russian offensive in the east, Zelensky is pushing ever harder for friendly nations to send tanks, jets and missiles.

Britain has already prepared 10,000 troops for battle and is currently training Ukrainian personnel to operate 14 Challenger 2 tanks, which will be deployed next month.

Sunak confirmed during Zelensky's historic visit that pilots from Ukraine were also now to be trained to fly NATO-standard combat aircraft.

"We want to get it done as quickly as humanly possible," the Downing Street spokesman said of the training, stressing no final decision had been made on whether to provide Kyiv with any jets.