Announcement comes as Kyiv says a Ukrainian soldier was killed in shelling by rebels in the east of the country.
The Russian-backed leaders of Ukraine’s two breakaway regions have announced a general mobilisation, spurring fears of a further escalation in fighting in the ex-Soviet country.
The announcements on Saturday came as pro-Russian rebels and Ukraine accused each other of fresh attacks, and Kyiv said a Ukrainian soldier had been killed in separatist shelling.
“I urge my fellow citizens who are in the reserves to come to military conscription offices. Today I signed a decree on general mobilisation,” Denis Pushilin, the leader of the so-called Donetsk People’s Republic, said in a video statement.
Pushilin claimed his region’s forces had prevented attacks he said were planned by the Ukrainian security services, and that the Ukrainian army had launched attacks – accusations that Ukrainian officials have vehemently denied.
“I appeal to all the men in the republic who can hold weapons to defend their families, their children, wives, mothers,” Pushilin added. ”Together we will achieve the coveted victory that we all need.”
The leader of the Luhansk separatist region, Leonid Pasechnik, followed Donetsk in issuing a general mobilisation order to prepare for “repelling aggression”.
Pasechnik said all men aged 18 to 55 were banned from leaving the area following the general mobilisation order.
Kyiv has repeatedly denied any plans to regain control of separatist-held areas using force or of the Crimean peninsula, which was annexed by Moscow in 2014.
Western leaders have for weeks raised the alarm over a build-up of Moscow’s army around Ukraine with Washington warning that an imminent attack could take place.
Kyiv said a Ukrainian soldier was killed on Saturday in clashes with separatists.
“As a result of a shelling attack, one Ukrainian soldier received a fatal shrapnel wound,” the joint military command for east Ukraine reported.
The Ukrainian military said on its Facebook page that it had recorded 19 ceasefire violations by the separatists since the start of the day compared with 66 cases over the previous 24 hours.
Separatists opened fire on more than 20 settlements, using heavy artillery, which has been banned by Minsk agreements, the military said.
More than 14,000 people have been killed in fighting between Ukraine’s army and Moscow-supported separatists since fighting broke out in 2014.
Meanwhile, evacuations of towns and villages in the Luhansk and Donetsk regions continued. According to the Donetsk separatists early on Saturday, more than 6,000 people have already been brought to safety, including 2,400 children. Shelters are ready for these people in the southern Russian region of Rostov.
The separatist leaders had called for people to flee on Friday, justifying the appeal with a threatened attack by Ukrainian government troops.