Ukraine's government said 32 tanks have crossed into the country from Russia, the BBC reported.
Kiev military spokesman Andriy Lysenko said a convoy crossed into the rebel-controlled Lugansk region on Thursday.
Lysenko said the convoy consisted of 32 tanks and 16 howitzer cannons, as well as 30 trucks containing troops and equipment.
He said that an additional column of trucks and three mobile radar stations crossed a different Lugansk border point, AFP reported.
The claims could further endanger the fragile ceasefire which has been in place in eastern Ukraine since Sept. 5. Despite the truce, hundreds have people have died in the area since then, the BBC reported.
The latest convoys mentioned by Kiev may not be the only ones to have crossed the border recently. BuzzFeed News' correspondent in the region reported a sighting of two columns moving into Ukraine last weekend.