Ukrainian authorities in the northeastern city of Kharkiv warned people not to go near what they said were landmines being dropped on the city.
On Monday, security forces cordoned off an area in the east of Kharkiv as they cleared a number of small devices scattered across residential streets.
Lieutenant Colonel Nikolay Ovcharuk, head of the demining unit of the state emergency service, said the devices were plastic PTM-1M mines, which detonate using timers and which were widely used by Soviet forces in Afghanistan.
"They have self-destructing timers," he said as loudspeakers warned people not to approach the cordoned-off area where mine disposal teams were working.
Reuters could not independently confirm the type of device. Scatterable landmines such as PTM-1M mines are prohibited under the Ottawa treaty on anti-personnel mines because of the risk of civilian casualties.
Earlier, authorities issued a warning that Russian forces had been dropping "parachute bombs" on Kharkiv, a major city close to the northeastern border with Russia that has been under bombardment for weeks.
Residents said the devices had been dropped in the early hours of Monday morning. "Tonight at 1 a.m. we heard some strange sounds, something whistled and then it all dropped," a local man who gave his name as Sergey said.
Ukrainian officials have repeatedly accused Russia of war crimes but Moscow, which launched its invasion of Ukraine on Feb. 24, has denied targeting civilians. Russia calls its actions in Ukraine a “special operation.”
(Reporting by Vitaliy Gnidyi; Editing by Lisa Shumaker)