The warring sides also exchanged prisoners in one of the few results of talks last week, and Russia reported new attacks on the front line.

According to their statement, Ukraine's Special Operations Forces infiltrated and attacked the Savasleyka airfield in Nizhny Novgorod, which Russia primarily uses for the deployment of MiG-31K fighters carrying Kinzhal ballistic missiles that have been used regularly in its conflict with Ukraine, a Guardian report said.

As well as 479 drones, 20 missiles of various types were fired at different parts of Ukraine, according to the air force, which said the barrage targeted mainly central and western areas of Ukraine.