Defence Secretary Ben Wallace said the UK had so far delivered 3,615 Next Generation Light Anti-tank Weapons (NLAWs) "and continue(s) to deliver more".

"We will shortly be starting the delivery of a small consignment of anti-tank Javelin missiles as well," he told parliament.

Wallace added that "in response to Ukrainian requests, the government has taken the decision to explore the donation of Starstreak high-velocity man-portable anti-air missiles".

Like NLAWs, the British Starstreak missiles are a mobile system designed to be fired by troops in the field, targeting helicopters and planes.

"We believe that this system will remain within the definition of defensive weapons but will allow the Ukrainian force to better defend the skies," the minister said.

"I want to assure the House (of Commons) that everything we do is bound by the decisions to supply defensive systems and are calibrated not to escalate to a strategic level."

Britain will also increase its supplies of rations, medical equipment and other "non-lethal" military aid to Ukraine, Wallace said.

Prior to Russia's invasion on February 24, Britain had sent a contingent of military trainers to instruct Ukrainian forces on using the anti-tank weapons.

It has sent 800 troops to Estonia to shore up NATO's eastern flank, and has another 1,000 on standby if the the humanitarian crisis worsens in Ukraine's neighbours.

But like other NATO allies, Britain has rebuffed Ukraine's demands to impose a no-fly zone, fearful of the risk of all-out war with nuclear-armed Russia.