Russian forces are intensifying their offensive against the key eastern Ukrainian city of Avdiivka, in an effort to capture the area.

The administration of President Vladimir Putin apparently aims to make an appeal of a victory there ahead of the presidential election in March.

Russia started deploying a large number of troops around autumn last year in an operation against the city, as part of its attempt to take control of the whole Donetsk region. Avdiivka is located about 15 kilometers north of the region's capital, Donetsk.

The troops have recently advanced close to a major coke and chemical plant in northern Avdiivka.

Oleksandr Tarnavskiy, a Ukrainian commander, said in a social media post on Friday that the situation was "difficult but controlled."

He went on to say, "Fierce battles are taking place within the city. Our troops are using all available forces and means to restrain the enemy."

Meanwhile, White House national security spokesperson John Kirby said on Thursday that Avdiivka is "at risk of falling into Russian control."

A US think tank, the Institute for the Study of War, said on Thursday that Russian forces are "conducting a tactical turning movement through Avdiivka likely to create conditions that would force Ukrainian troops to withdraw from their positions in the settlement."

The institute also said Ukrainian troops "have yet to fully withdraw from the settlement and continue to prevent Russian forces from making gains."

The institute also said the potential capture of Avdiivka would give the Kremlin a "battlefield victory" to "promote to a domestic audience ahead of the Russian presidential election."