The Ukrainian president has again accused Russian army officers of fighting alongside pro-Moscow separatists in the east of the country.
Petro Poroshenko said: "Russian staff officers are taking part in military operations against Ukrainian forces."
The war of words between Kiev and Moscow followed a weekend of intense fighting, in which Ukrainian forces say they inflicted heavy losses on pro-Russian rebels.
More top news
A band of cloud and patchy rain, occasionally heavy, will move across western parts during the day.