Prime Minister Rishi Sunak has said "nothing is off the table" after Volodymyr Zelensky urged the UK to supply Ukraine with fighter jets.
Ukraine's president, who was visiting the UK for the first time since Russia's invasion, expressed gratitude for the equipment received so far.
But he warned that supplies were "running out" and that this could result in "stagnation" in the conflict.
The UK is to start training Ukrainian forces to fly Nato-standard jets. sa game
Downing Street said Defence Secretary Ben Wallace is investigating what aircraft the UK could potentially offer, but emphasised this was "a long-term solution" and that training pilots could take years.