Ukraine is planning to draft another 160,000 troops into its military as Russia gains ground in the east.
Russia has been advancing in the eastern Donetsk region and on Tuesday said it had fully captured the mining town of Selydove.
It also comes amid reports that a number of North Korean troops have been deployed to Russia.
Ukraine’s military has been under severe pressure of late, in part due to Russia’s greater manpower and deeper resources.
“There are plans to call up more than 160,000 people,” the secretary of Ukraine’s National Security Council, Oleksandr Lytvynenko, told parliament on Tuesday.
The AFP news agency reports the recruitment will take place over three months.
The announcement comes as Ukraine continues to commit personnel for its incursion in the Kursk region of Russia, which started in August.
The Pentagon estimates around 10,000 North Korean troops have been deployed to train in eastern Russia.
The US said on Tuesday a “small number” of North Korean troops have been sent to Kursk. A couple of thousand more are heading there, it said.
Last week, President Vladimir Putin refused to deny that North Korean troops had arrived in Russia, following reports that Pyongyang was preparing to send thousands of troops to aid its ally.
The latest mobilisation comes after Ukraine’s parliament passed legislation in April to help mobilise troops to fight invading Russian forces.
The law requires every man aged between 25 and 60 to log their details on an electronic database so they can be called up. Conscription officers are on the hunt for those avoiding the register, pushing more men who do not want to serve into hiding.
The measure is aimed at boosting numbers in the military, which is under severe pressure as Russia continues to make gains in the east.
Moscow has announced that it now controls all of Selydove in the Donetsk region as well as surrounding villages, as it focuses on the city of Pokrovsk.
This is a strategically significant transport hub, just 18km (10 miles) away.
