A Ukrainian drone strike, among the deepest into Russia in more than three years of the war, has forced a temporary suspension of production at an electronics company in the Volga river region of Chuvashia, the head of the region says.

The strike, some 1,300 km (800 miles) from the border with Ukraine, caused no casualties, Chuvashia Governor Oleg Nikolayev said in a statement on the Telegram messaging app.

But "the responsible decision was made to temporarily suspend production to ensure the safety of employees" of the VNIIR enterprise where the drones fell, Nikolayev said.

It was not immediately clear whether the drones caused any damage. Nikolayev said that another drone fell onto some fields in the area of the capital of the region, Cheboksary.

Ukraine's military said in a Telegram statement on Monday that "at least two drones" hit the VNIIR facility that specialises in manufacturing navigation equipment used in attack drones, guided aerial bombs and high-precision weapons.

The Ukrainian military said the drone attack sparked a large-scale fire at the VNIIR plant.

The Russian defence ministry - which reports only how many drones were destroyed not how many Ukraine launched - said on Telegram that its units downed two drones over Chuvashia. In total, it said, air defence systems destroyed 49 Ukrainian drones overnight over Russia.

Kyiv has often said that its attacks inside Russia are aimed at destroying infrastructure key to Moscow's war efforts and are in response to the continued Russian strikes on Ukraine.

The VNIIR Russian Scientific Research Design and Technological Institute of Relay Engineering with experimental production in Chuvashia is on the U.S. sanctions list, according to the US Treasury website.

A Ukrainian drone attack on the Voronezh region that borders Ukraine damaged a gas pipeline, cutting off gas supplies to 22 clients, the region's governor, Alexander Gusev, said on the Telegram.