Following warnings of increased activity from pro-Russian separatists near the Ukrainian border, the country's parliament voted on Thursday to replenish its front-line military forces and resume partial conscription, reported Reuters.

"Russian aggression is continuing," Oleksander Turchynov, secretary of the national defense council, warned Ukraine's parliament. "There has been a significant surge in the intensity of firing."

"There is an urgent need to strengthen the combat and mobilization readiness of our forces and other military forces up to a level which guarantees an adequate reaction to threats to national security from continuing Russian aggression," he said.

Turchynov said that 8,500 Russian regular army forces were now deployed in eastern Ukraine to back the 30,000 rebels already fighting there, adding that around 52,000 Russian troops were deployed along the Ukraine border with tanks, armored vehicles, artillery and military helicopters.

He said that a "large-scale continental war" could erupt if Russian troops continue to become more involved.

Another possibility described by Turchynov would see Russia continue to prevent stabilization in Ukraine, which could result in the country exhausting its economic and defense resources and prevent it from integrating more closely with the West, reported AFP.

Heeding Turchynov's warning, Ukraine's parliament passed a law that will send three waves of reserve troops to the border this year. The first will include some 50,000 people and is set to be dispatched on Jan. 20.

Separatist leader Alexander Zakharchenko responded to the moves, saying, "Ukraine is preparing for war. We are ready to respond adequately. We are not weak."

On Tuesday, 12 Ukrainian civilians were killed after their bus was hit by artillery while stopped at an army checkpoint. Kiev blamed the separatists for the attack, but they said they were not responsible, according to Reuters.

Russia continues to deny any involvement in the conflict in which more than 4,700 have been killed, insisting it hasn't sent troops or weapons into eastern Ukraine.