By Pavel Polityuk and Vladislav Smelyanets

KYIV/KRAMATORSK, Ukraine (Reuters) - Ukraine said on Monday it was reinforcing its forces in the eastern Donbass region and repelling persistent attacks by the Wagner Group of mercenaries on Bakhmut and other towns there.

The Ukrainian authorities added that the reinforcements were sent to Solidar, a small town near Bakhmut where the situation is very difficult.

"The enemy again made a desperate attempt to attack the city of Solidar from different directions, bringing into battle the most professional units of the Wagner Group," the Ukrainian army said in a statement.

Ukrainian President Volodymyr Zelensky said in a video recording on Sunday evening that Bakhmut and Solidar were holding out despite the widespread destruction.

"Our soldiers are repelling the continuous Russian attempts to advance," he added. He added that "things are very difficult" at Solidar.

In the north, in the Kharkiv region, a Russian missile attack on a market in the village of Shevchenkov killed a 60-year-old woman and wounded seven, including a 13-year-old girl, said regional governor Oleh Snihopov.

Rescue workers searched huge piles of debris, overturned and burned vending booths, and a huge hollow in the ground, according to a video posted by the Ukrainian public broadcaster on the Telegram application.

Andriy Yermak, director of the Ukrainian President's Office, wrote on Telegram "market terrorists", condemning the attack.

Yevgeny Prigozhin, founder of the private military group Wagner, which has been trying to seize Bakhmut and Solidar for months in a grinding war that claimed many lives on both sides, said on Saturday that the importance of Bakhmut lies in the network of mines there.