The UK's Prime Minister Boris Johnson has warned against what he called "Ukraine fatigue" setting in around the world after nearly four months of war.

Returning from a visit to the capital, Mr Johnson stressed the importance of allied nations showing they would stand by Kyiv for the long-term.

Meanwhile, Ukraine's president paid a visit to the southern cities of Mykolaiv and Odesa, where Ukrainian soldiers are holding out against Russian shelling.

Volodymyr Zelensky inspected damaged buildings and met soldiers, officials and health workers, his office said.

The Ukrainian president has met several Western leaders who have traveled to Kyiv. But he has also visited areas where fighting has been raging, in what is seen as a show of defiance aimed at Russia.

The Mayor of Kyiv, Vitali Klitschko, told the BBC the Russian public will eventually realise their young soldiers are dying for nothing more than Russian President Vladimir Putin's ambitions.

The former world heavyweight boxing champion was attending the funeral of a well-known 24-year-old anti-corruption activist when the remarks were made.

Volunteer soldier Roman Ratushny was killed in Izyum, in the Kharkiv region, on 9 June.

Mayor Klitschko, who won legions of fans across the world during his long record-breaking career, said the Russian leader was destroying millions of lives in both Ukraine and his own country.

"This is also a tragedy for Russians and for the Russian Federation. The people do not understand that right now, but I am sure they will realise very soon the reality," he said.

"The Russians die - for what? The ambition of Putin?"