NEAR KREMINNA, Ukraine, (Reuters) - Russian forces attacked northern and southern stretches of the front in Ukraine's eastern Donbas region yesterday, even as Kyiv said Moscow's assault was flagging near the city of Bakhmut.

Ukrainian military reports described heavy fighting along a line running from Lyman to Kupiansk, as well as in the south at Avdiivka on the outskirts of the Russianheld city of Donetsk.

Both areas have been major Russian targets in a winter campaign to fully capture Ukraine's industrialised Donbas region. The offensive has so far yielded scant gains despite the deaths of thousands of troops on both sides in the war's bloodiest fighting.

At a Ukrainian artillery position in lush pine forests behind the northern stretch of the front, troops fired 155 mm rounds from a French TRF-1 howitzer towards a highway used to supply Russian-held Kreminna.

"Luckily we are holding the same position," a soldier told Reuters. "Because we are facing a very strong enemy with very good arms. And it's a professional army: airborne troops."

As orders came in with coordinates, the crew jumped into position, removed camouflage, aimed, loaded and fired. After three rounds, they lowered their gun's barrel, covered it back up and returned to bunkers to await further orders. Artillery and small arms fire could be heard in the distance.

The front lines have barely budged since November, despite intense fighting. Ukraine recaptured swathes of territory in the second half of 2022, but has since kept mostly to the defensive, while Russia has attacked with hundreds of thousands of freshly called-up reservists and convicts recruited from prison.

As winter turns to spring, the main question in Ukraine is how much longer Russia can sustain its offensive, and when or whether Ukraine can reverse the momentum with a counterassault.

Meeting in Ottawa on Friday, U.S. President Joe Biden and Canadian Prime Minister Justin Trudeau reaffirmed their "steadfast support for the Ukrainian people as they defend themselves against Putin's brutal and barbaric invasion," Trudeau said.

On Thursday, the commander of Ukrainian ground forces said Russia's assault on Bakhmut, a small city that has been the focus of the biggest battle of the war, appeared to be losing steam and Kyiv could go on the offensive "very soon".

For now, Ukrainian forces are still focused on preventing a Russian advance along more than 300 km (185 miles) of Donbas front, from Kupiansk in the north to Vuhledar in the south.