Ukraine has launched a “large-scale” drone attack against Russian military bombers in Siberia, striking more than 40 warplanes thousands of kilometres from its own territory, a security official said.

The claims could not be independently verified. But if confirmed, the attacks would mark Ukraine’s most damaging drone strike of the war to date, amid an escalation in cross-border incursions before planned peace talks in Istanbul on Monday.

“Ukrainian security services are carrying out a large-scale special operation aimed at destroying enemy bombers far from the front, in Russia,” the official was quoted by Agence France-Presse as saying, adding a fire had broken out at the targeted Belaya airbase.