[Jimbuna]

Russian billionaire Roman Abramovich suffered symptoms of suspected poisoning at talks in Kyiv earlier this month, sources close to him confirm.

He has since recovered but experienced symptoms including peeling skin, red eyes, and constant tearing, the Wall Street Journal reports.

Russia is meanwhile developing measures to restrict entry into country for nationals of "unfriendly" countries, its foreign minister says.

The government has previously included the US, UK and EU nations on a list of such states.

Ukraine closed humanitarian corridors from its cities on Monday due to warnings of Russian "provocations" on routes.

The mayor of Mariupol says the besieged port city is on the verge of catastrophe and must be completely evacuated.

The next round of face-to-face negotiations between Ukraine and Russia take place this week in Turkey.