David Cameron (Photo: EPA/ Mohammed Badra)

Ukraine has the right to use weapons provided by the United Kingdom to strike targets inside Russia, because Moscow strikes on Ukrainian territory, British Foreign Secretary David Cameron told Reuters.

He also promised £3 billion (€3.5 billion) in annual military aid to Ukraine "as long as is necessary".

"Ukraine has that right. Just as Russia is striking inside Ukraine, you can quite understand why Ukraine feels the need to make sure it's defending itself," Cameron said while in Kyiv.

The diplomat said that the country will provide financial assistance "as long as it takes."

"We've just really emptied all we can in terms of giving equipment," he noted.

Cameron welcomed the US allocation of new military aid to Ukraine, but avoided a direct answer to a question about how he thought the possible re-election of Republican candidate Donald Trump might affect America's support for Ukraine.

"It's not for us to decide who the Americans choose as their president – we will work with whoever that is," the foreign secretary said.

Overnight on March 22-23, a fire broke out and explosions rang out at the Novokuibyshev Oil Refinery in Russia's Samara Oblast. According to Andriy Yusov, a representative of the Main Intelligence Directorate of the Ministry of Defense, "an incident occurred" there.

On the morning of April 2, drones attacked an enterprise in Yelabuga. LIGA.net's source in the law enforcement agency said that the Ukraine's Defense Intelligence was behind these strikes.

Overnight on April 19-20, the Security Service of Ukraine, military intelligence, and the Special Operations Forces of the Armed Forces of Ukraine launched a large-scale drone attack on eight Russian regions, targeting the energy infrastructure. In particular, oil refineries in Smolensk Oblast were hit by drones.

Overnight on April 26-27, the SBU launched a massive drone attack on a military airfield and two oil refineries in Krasnodar Krai.