A White House official has urged US Congress to pass a budget bill to provide urgent funding to Ukraine, warning that Russia may capture a town in eastern Ukraine.

White House National Security Communications Advisor John Kirby spoke to reporters on Thursday about Russia's ongoing military attempts to encircle and capture Avdiivka in the eastern region of Donetsk.

Kirby said the White House has heard from Ukrainians that the situation is critical. He said Russia continues pressing Ukrainian positions every single day, and that "Avdiivka is at risk of falling into Russian control. "

Kirby said Ukrainian forces on the ground are running out of artillery ammunition in the battle for Avdiivka. He said the United States has not been able to provide Ukraine with "the artillery shells they desperately need to disrupt these Russian assaults."

The US Senate approved a foreign aid package on Tuesday, including funds for Ukraine and Israel. But it remains unclear whether the budget bill can clear the Republican-controlled lower house.