Ukraine's military said Russian tanks and soldiers disguised as separatists have entered the country, an accusation that comes as Russia's foreign ministry announced plans to send another aid convoy across the border "in the next few days."

Ten tanks, two armored vehicles and a group of disguised Russian troops passed the border near southeastern Ukraine on Monday, military officials told Reuters. Border guards stopped the armoured vehicles near the town of Novoazovsk before it reached its destination in Mariupol city.

Military officials accused Russia of attempting to form another rebel stronghold in Ukrain's southern regions, which would reinforce pro-Russian separatists that have already seized Donetsk and Luhansk cities in the east.

"This morning there was an attempt by the Russian military in the guise of Donbas (separatists) fighters to open a new area of military confrontation in the southern Donetsk region," military spokesman Andriy Lysenko said, Reuters reported.    

Russian Foreign Minister Sergei Lavrov denounced Ukraine's latest accusation that it's doing the utmost to assist the uprising.

"I have not heard of this, but there is plenty of disinformation out there about our 'incursions' " Lavrov said according to the BBC.

Lavrov also said Russia is making plans to send another convoy filled with aid into eastern Ukraine "in the next few days." Last week, a Russian aid convoy made its way to Luhansk city meant for thousands of residents affected by the five-month conflict that has killed 2,000 people. Another 333,000 people have been displaced, according to the BBC.

The current conflict dates back to February when then Russian-allied president Viktor Yanukovych was ousted after weeks of protest. Once a Western-backed government took over, Russian President Vladimir Putin annexed Ukraine's eastern Crimea peninsula in March, claiming a need to protect the area's significant ethnic Russian population.

Ukrainian troops have engaged in a deadly conflict with pro-Russian separatists ever since.