A man opened fire and wounded a recruitment officer at an enlistment centre in Siberia on Monday, the local governor said, as tensions mount over Russia's military mobilisation for the conflict in Ukraine.

The incident occurred in the town of Ust-Ilimsk in Irkutsk, a vast and thinly populated region of southeastern Siberia. 

"In Ust-Ilimsk, a young man fired at the military registration and enlistment office," Irkutsk governor Igor Kobzev said in a message on Telegram.

Kobzev said a military commissar had been wounded in the shooting and was in critical condition.

The shooter was immediately arrested, he said, and "will definitely be punished!"

"I am ashamed that this is happening at a time when, on the contrary, we should be united. We must not fight with each but against real threats," Kobzev said. 

"I have given instructions to strengthen security measures. I ask everyone to remain calm," he said.

Russian President Vladimir Putin announced a partial mobilisation of reservists on Wednesday as Moscow's forces face setbacks in the seven-month conflict in Ukraine. 

The announcement sparked panic and demonstrations, with hundreds detained across the country.

Critics have accused authorities of focusing mobilisation efforts in remote parts of the country like Siberia and the North Caucasus, to avoid sparking opposition in major urban centres and especially Moscow.