Ukrainian forces have repelled Russian attempts to advance into the center of the small eastern city of Bakhmut, a top Ukrainian general said on Tuesday.

The months-long battle for Bakhmut has become one of the bloodiest of Russia's nearly 13-month-old war in Ukraine.

"Assault groups of the enemy are trying to advance from the outskirts to the center of the city but our defense forces are working and destroying them 24/7," Oleksandr Syrskyi, the Commander of Ukrainian Ground Forces, wrote on the Telegram messaging app.

He said there was intense fighting along the eastern front line.

Reuters could not independently verify the situation in Bakhmut.

Russia has made the capture of Bakhmut a priority in its strategy to take control of Ukraine's Donbas industrial region. If Russian forces capture Bakhmut, it will be Moscow's first significant territorial gain since last summer.

Deputy Defence Minister Hanna Malyar said no one had believed Bakhmut would hold out under such intense attacks for so long.

Naming three generals and two colonels leading Bakhmut's defense, she thanked them for their leadership and thousands of soldiers for their bravery.

".. the defense of Bakhmut is holding and the possibilities are not yet exhausted," Malyar said.