Britain and the United States are stepping up their military aid to Ukraine as Russia continues missile attacks on Ukraine's cities and infrastructure.

The British Defence Ministry said in a social media post on Saturday that it had provided precision-guided missiles to the Ukrainian forces.

The ministry said those missiles will be used to attack targets, such as armored vehicles and tanks, and to stall Russian advances.

The Biden administration in the US is finalizing plans to send the Patriot missile defense system to Ukraine in a bid to help boost the country's air defense capabilities.

US media report that the plans will likely be approved soon.

Russia has reacted sharply to the proposed US weapons transfer, calling it "yet another provocative step."

Russia's massive missile attacks on the Ukrainian capital Kyiv and eastern and southern parts of Ukraine on Friday killed four people.

The Russian attacks also hit Ukraine's power-generating facilities, causing blackouts in extensive areas.

In Kyiv, the supply of electricity, water and heat had been restored by Sunday.

But in areas around the capital, the power supply was down to about 50 percent.