Russia reportedly moves dozens of tanks, trucks and howitzer cannons into Ukraine
The reported move comes only two months after a cease-fire was agreed to by both countries.
"Supplies of military equipment and enemy fighters from the Russian Federation are continuing," said Lysenko, according to the BBC.
The truce has rarely been honored by either side in the months since. Five Ukrainian soldiers have been killed, and an additional 16 injured, Lysenko added.
Russian officials denied the reports in comments to Interfax, according to Deutsche Welle. The defense ministry spokesperson called the claims a "provocation."
NATO earlier this week detailed troop movements along the Russia-Ukraine border.
The military units appear to have moved into the self-declared "People's Republic of Donetsk," a loosely affiliated group of rebels seeking to separate from the Kiev-based Ukrainian government.
The newly-formed country held elections this past weekend, according to Deutsche Welle.
Fighting began earlier this year when Russia seized Crimea from Ukraine in March following the resignation of Prime Minister Viktor Yanukovich -- a Putin ally.
He left office after thousands took to the streets to protest his decision to put on ice a proposal for Ukraine to join the European Union.
Parts of Eastern Ukraine have since come under control of pro-Russia rebels, leading many to fear the former Soviet-block country could fall into an all-out civil war.
The Russian government has repeatedly denied Western government and media claims it has supported the rebels in their fight against Ukraine.
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