Russian forces have been stepping up their Iranian drone operation against Ukraine.

The latest assessment by the British Ministry of Defence says Iranian drones have been a core element of Russia's campaign of long-range strikes into Ukraine.

Meanwhile, a Ukrainian Air Force spokesperson is expecting a record number of Russian drone attacks on the country this winter.

Yurii Ihnat said on Sunday that Russia's use of Iranian-designed drones this autumn and winter will smash last year's figure. He said more than 500 Iranian-made drones were used in September alone. About 1,000 were used in a six-month period that included last winter.

Ihnat said Kyiv needs to quickly come up with countermeasures.

Russian drone attacks on Ukrainian infrastructure facilities last year left the country with acute power shortages. Officials warn that such shortages could happen again this winter.

Monday's assessment by the British defense ministry says Russia's partnership with Iran has strengthened in recent years. It says Iranian military aid for Russia's campaign in Ukraine has included hundreds of uncrewed aerial vehicles and artillery munitions. It adds that this arrangement has now been extended to include assembling and producing the drones under license at a facility in Russia.