(Reuters) -U.S. President Joe Biden and Russia's Vladimir Putin have agreed in principle to hold a summit on the Ukraine crisis, the office of French President Emmanuel Macron said on Monday.

       "The substance will have to be prepared by (U.S.) Secretary Blinken and (Russian Foreign) Minister Lavrov during their meeting on Thursday 24 February," the Elysee palace said https://www.elysee.fr/en/emmanuel-macron/2022/02/20/spoke-with-the-president-biden-and-the-president-poutine.

       "It can only be held at the condition that Russia does not invade Ukraine."

       Macron will help prepare the contents of the discussions, the statement added.

       (Reporting by Raphael Satter; writing by Costas Pitas; Editing by Kim Coghill and Lincoln Feast.)