(Reuters) - Russian forces launched a missile attack on a large Ukrainian military facility near the Polish border on Sunday, officials said, in what appeared to be the westernmost attack of the war, and air raid sirens again woke residents in the capital Kyiv.

"The occupiers launched an air strike on the International Center for Peacekeeping and Security" in Yavoriv, the Lviv regional military administration said in a statement. "According to preliminary data, they fired eight missiles."

Initial reports indicated "there are no dead, but information about the injured and wounded is being clarified," said Anton Mironovich, spokesman for the Academy of Land Forces of the Ukrainian Armed Forces, according to Interfax Ukraine news agency cited.

The 360 square-km (140 square-mile) facility less than 25 km (15 miles) from the Polish border, is one Ukraine's biggest and the largest in the western part of the country. Ukraine holds most of its drills with NATO countries there.

The mayor of another city in western Ukraine, Ivano-Frankivsk, said Russian troops also continued to hit its airport, with no initial reports of casualties.

Ukrainian President Volodymyr Zelenskyy has warned Russian forces they face a fight to the death if they try to occupy the capital Kyiv, as air raid sirens again woke residents on Sunday morning.

"If they decide to carpet bomb and simply erase the history of this region ... and destroy all of us, then they will enter Kyiv. If that's their goal, let them come in, but they will have to live on this land by themselves," Zelenskyy said on Saturday.

The president, who has repeatedly appeared on social media from the capital, said some small towns no longer existed in the third week of Russian attacks, the biggest assault on a European country since World War Two.

Russian shelling has trapped thousands of people in besieged cities and sent 2.5 million Ukrainians fleeing to neighbouring countries.

Ukraine accused Russian forces on Saturday of killing seven civilians in an attack on women and children trying to flee fighting near Kyiv. France said Russian President Vladimir Putin had shown no readiness to make peace.

The Ukrainian intelligence service said the seven, including one child, were killed as they fled the village of Peremoha and that "the occupiers forced the remnants of the column to turn back."

Reuters was unable immediately to verify the report and Russia offered no immediate comment.

Moscow denies targeting civilians since invading Ukraine on Feb. 24. It blames Ukraine for failed attempts to evacuate civilians from encircled cities, an accusation Ukraine and its Western allies strongly reject.

Zelensyy said Moscow was sending in new troops after Ukrainian forces put 31 of Russia's battalion tactical groups out of action in what he called Russia's largest army losses in decades. Reuters could not verify his statements.

"We still need to hold on. We still have to fight," Zelenskyy said in a video address late on Saturday, his second of the day. Saying about 1,300 Ukrainian troops had been killed, he urged the West to get more involved in peace negotiations.

The United States said it would rush up to $200 million in additional small arms, anti-tank and anti-aircraft weapons to Ukraine, where officials have pleaded for more military aid.