President Volodymyr Zelenskiy met British Prime Minister Boris Johnson, one of his staunchest backers, in Kyiv on Saturday, in a visit that was not announced in advance.
Johnson used the visit to set out a new financial and military aid package for Ukraine.
He was the latest foreign leader to visit Kyiv after Russian forces pulled back from the outskirts of the capital last week.
The move caps weeks of lobbying by the British prime minister to meet Zelenskiy to underline their close ties.
Andriy Sybiha, deputy head of the Ukrainian president’s office, said on Facebook that Johnson’s visit had begun with a one-on-one meeting with Zelenskiy.
Zelenskiy’s office published pictures showing the two men chatting across a table.
Johnson met Zelenskiy “in a show of solidarity with the Ukrainian people”, a Downing Street spokesperson said.
On Zelenskiy’s Telegram channel, Johnson was described as “one of the most principled opponents of the Russian invasion, a leader in putting sanctions on Russia and providing defensive support to Ukraine”.
“The UK will send more defensive weapons to Ukraine and will work with G7 partners to target every pillar of the Russian economy to ensure Putin fails,” Johnson tweeted earlier on Saturday.
Ukraine is ready for a tough battle with Russian forces amassing in the east of the country, Zelenskiy said.
Earlier in the day, the Ukrainian leader met Austrian Chancellor Karl Nehammer in Kyiv, warning in a joint news conference that while the threat to the capital has receded, it is gaining in the east.
“Yes, (Russian) forces are gathering in the east (of Ukraine),” Zelenskiy said.
“This will be a hard battle, we believe in this fight and our victory. We are ready to simultaneously fight and look for diplomatic ways to put an end to this war,” Zelenskiy added.