Sir Keir Starmer has said "the focus must remain on Ukraine" despite the Iran war, as he meets President Volodymyr Zelensky in Downing Street.

Welcoming the Ukrainian leader to No 10, the prime minister said: "Putin can't be the one who benefits from a conflict in Iran, whether that's oil prices or the dropping of sanctions."

The US has temporarily eased sanctions on some Russian oil in an attempt to tackle surging prices triggered by the conflict in the Middle East.

During the meeting, the leaders will agree a new defence partnership aimed at tackling cheap attack drones.

Downing Street said the deal would bring together "Ukrainian expertise and the UK's industrial base" to manufacture and supply drones and other capabilities.

Under the partnership between the UK and Ukraine, closer co-operation in the defence industries will also be sought with third countries as part of efforts to bolster international security.

Britain will also give £500,000 to fund an AI centre of excellence in Kyiv.

The two leaders are also expected to discuss further support for Ukraine against Russia's full-scale invasion, now in its fourth year.

Meanwhile, Zelensky also met the King at Buckingham Palace and was invited to take tea with the monarch in his private study during a 25-minute meeting.

Ahead of the meeting, Sir Keir reiterated the UK's support for Kyiv, saying: "Our resolve is unbreakable."

"There's obviously a conflict in Iran going on, in the Middle East, but we can't lose focus on what's going on in Ukraine and the need for our support," he added.

Zelensky thanked the UK for its backing, saying: "You have stood with us all through this difficult winter."

He said the pair would discuss battlefield developments, energy security and negotiations to end the war with Russia and the US.

In a statement ahead of the meeting, UK Defence Secretary John Healey said it was "increasingly important that we build on Ukrainian expertise and innovation".

Sir Keir said: "Drones, electronic warfare and rapid battlefield innovation are now central to national and economic security, and that has only been further magnified by the conflict in the Middle East.

"By deepening our defence partnerships, we are strengthening Ukraine's ability to defend itself from Russia's brutal, ongoing attacks, while ensuring the UK and our allies are better prepared to meet the threats of the future."

It comes as the US-Israeli war with Iran enters a third week, while US President Donald Trump continues to criticise the UK and other countries over the extent of their response to the conflict.

Rising oil prices are fuelling Russia's war machine, while Ukraine's allies are distracted and divided over the Middle East.

Zelensky is currently on a tour of European capitals to shore up support and keep his conflict at the forefront of allies' minds.

In his overnight address on Monday, Zelensky said he was working with allies to boost Ukraine's defences, but the key to peace was putting more pressure on Russia.

Last week, teams of Ukrainian military experts were sent to Qatar, the United Arab Emirates and Saudi Arabia to help them defend against drones launched from Iran.

Zelensky said Ukraine had "the greatest experience in the world in countering attack drones". In its fight against Russia, Ukraine has been using cheap, mass-produced interceptor drones to keep defend its skies.