Ukraine's former president Petro Poroshenko on Friday warned his successor to never trust anything Russia's Vladimir Putin says and avoid meeting him one-on-one, three days before crunch talks in Paris.

"Don't trust Putin. Ever and in anything. Putin manipulates everything: content, facts, figures, maps, emotions. He hates Ukraine and Ukrainians," Poroshenko, who was defeated by Volodymyr Zelensky in this year's polls, wrote in an editorial.

"I sincerely advise to avoid meeting one-on-one with Putin, and if this is impossible, resist his KGB manipulations and flattery," Poroshenko wrote in Ukrainska Pravda online daily.

Zelensky, a political novice who was inaugurated in May, will meet Putin for the first time on Monday to hold talks on the conflict in Ukraine with mediation from Germany's Angela Merkel and France's Emmanuel Macron.

The summit is the first since 2016 in this format, and is awaited by some in Ukraine with hope and others with unease and concern that Zelensky may compromise the country's interests when faced with political heavyweight Putin. Putin last month praised Zelensky as "likeable" and "sincere".

His spokesman Dmitry Peskov on Friday told journalists the Russian leader is headed to Paris with "serious intent" and plans to hold bilateral meetings with the three heads of state, as well as discuss the Ukraine conflict together.