Fierce fighting continues in Ukraine as Russian forces fired missiles into the capital Kyiv while Ukrainian troops launched counterattacks in the east.

Ukrainian authorities say one person was injured after the Russian military attacked two districts in Kyiv with missiles on Sunday.

Mayor Vitali Klitschko said on social media that the missiles hit the Darnytski and Dniprovski districts on the eastern side of the Dnipro River.

The Russians are stepping up their offensive in the Luhansk region to take full control of the Ukrainian stronghold of Severodonetsk, but are facing resistance.

Ukrainian forces are intensively shelling Russian-held areas in the neighboring Donetsk region.

Pro-Russian militants say Ukrainians are using large howitzers provided by the United States and powerful multiple rocket launchers, adding that more than 640 rockets landed in Donetsk on Saturday and Sunday.

Russian President Vladimir Putin warned against Western nations' military aid to Ukraine in an interview with state-run television broadcast on Sunday.

He said that if long-range rocket systems are supplied to Kyiv, Russia will draw conclusions and strike those facilities that currently remain unaffected.

Russian Foreign Minister Sergey Lavrov indicated that Western sanctions will only have a limited impact.

In a TV interview on Saturday, Lavrov said that considering the level of international energy prices that has been established as a result of the West's policies, Russia has suffered no budgetary losses.

He also said profits from exporting energy resources will significantly increase this year.