Ukraine said Monday that "another massive attack" on Kyiv had killed at least five people, a day after the country's top military commander vowed to intensify strikes on Russia.

Diplomatic efforts to end the three-year war have stalled, with the last direct meeting between the two sides almost three weeks ago and no follow-up talks scheduled.

AFP journalists in Kyiv heard the buzzing of a drone flying over the city center and explosions, as well as gunfire.