At least 30 people were killed in a Russian attack on a civilian bus in Kramatorsk, Donetsk region, according to the State Emergency Service. (EPA Images pic)

KYIV: Ukrainian president Volodymyr Zelensky accused the US of being unwilling to help Ukraine after a Russian bomb attack on Thursday killed at least 35 people in the east, sending the two-day death toll from Russian strikes to over 70.

Hours after the strike on the embattled city of Kramatorsk tore through two buses, Zelensky criticised Washington's effort to pursue economic ties with Russia while also seeking to mediate the more than four-year war.

City authorities reported a new drone attack in the evening that killed two people. That brought to 35 the total death toll in the city.