Boris Johnson has met President Volodymyr Zelensky in Kyiv in a “show of solidarity” with Ukraine, Downing Street has said.

A No 10 spokesman said the Prime Minister was using the unannounced visit to set out a new package of financial and military aid.

“The Prime Minister has travelled to Ukraine to meet President Zelensky in person, in a show of solidarity with the Ukrainian people,” the spokesman said.

“They will discuss the UK’s long term support to Ukraine and the PM will set out a new package of financial and military aid.”

A picture of the meeting was posted online by the Ukrainian embassy in London.

Mr Johnson later posted his own picture of the meeting on Twitter, saying he was there “as a show of our unwavering support for the people of Ukraine”.

Mr Johnson’s visit comes the day after he announced a further £100 million worth of UK military assistance for the Ukrainian forces, including anti-tank and anti-aircraft weaponry and so-called “suicide drones”, which loiter over the battlefield before attacking their target.

It followed an appeal from the Ukrainians to western nations to send more arms as they prepare for the expected Russian offensive in the east of the country, after Moscow pulled back its forces from around Kyiv.

Earlier Mr Zelensky called on the international community to hold to account Russian forces who carried out a missile strike on a crowded railway station, killing at least 52 people.

The station at Kramatorsk was packed with women and children trying to flee west before the Russian advance arrives, when the missile hit on Friday.

“All world efforts will be directed to establish every minute of who did what, who gave what orders, where the missile came from, who transported it, who gave the command and how this strike was agreed,” Mr Zelensky said in his nightly video address.

The Kremlin has denied responsibility for the attack, but western officials believe it was probably a Russian Tochka-U missile, which Nato refers to as a SS-21, which was fired indiscriminately towards the town centre.

Mr Johnson’s visit comes the day after European Commission president Ursula von der Leyen was in the Ukrainian capital, and visited the town of Bucha, where civilians were reportedly raped and killed by occupying Russian troops.

Last month the prime ministers of Poland, the Czech Republic and Slovenia visited Kyiv in a show of support for the Ukrainians.