Boris Johnson has arrived in Ukraine for face-to-face talks with President Volodymyr Zelensky.
The Ukrainian embassy in London tweeted a picture of the two leaders holding a meeting in Kyiv, alongside the word 'surprise' on Saturday afternoon.
The visit comes less than 24 hours after the Prime Minister announced a new £100m military aid package for Ukraine, comprised of NLAWs, Javelins and other military hardware.
A Downing Street spokesman said the Prime Minister was using the unannounced visit to set out the details of the new financial and military aid package for Ukraine, announced on Friday.
"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."