Russia's Defense Ministry said on Wednesday that newly mobilized reservists in the Kaliningrad region have started combat training at the base of Russia's Baltic Fleet.

"All mobilized military personnel comply with the standards for shooting from small arms. In addition, citizens called up from the reserve restore their skills in the operation and maintenance of weapons, military and special equipment," the ministry said on its Telegram channel.

Courses have been also held to increase firing skills and prepare military personnel for "confident actions on the battlefield".

President Vladimir Putin ordered Russia's first military mobilization since World War Two last week, which could see hundreds of thousands more people sent to fight in Ukraine.

Russia has a significant military presence in Kaliningrad, a Russian Baltic coast enclave located between NATO and European Union members Poland and Lithuania, including nuclear-capable missiles, its Baltic fleet and tens of thousands of soldiers.