Moscow, March 3 (RHC)-- Russia's Federal Border Guard Service reported that Moscow is concerned about a “humanitarian catastrophe” in Ukraine as new figures show that an estimated 675,000 Ukrainian citizens have arrived in Russia in January and February this year.

Hundreds of Russian troops are reportedly heading towards the autonomous region of Crimea in southern Ukraine as the political crisis continues in the former Soviet state. Based on eyewitness reports, some 12 military trucks carrying troops, two ambulances, and a Tiger vehicle armed with a machine gun were on the road on Sunday from the Ukrainian city of Sevastopol, the home to Russia's Black Sea fleet, to Simferopol, Crimea’s administrative center.

This comes after Yevgeny Savchenko, the governor of Russia's Belgorod region, said armed groups were trying to cut off the road leading to neighboring Ukraine. According to recent reports, Kiev has also called up all military reservists in preparation for a possible military conflict in the region.

Andriy Parubiy, the chief of the national security and defense council of Ukraine, told reporters on Sunday that he had issued the call-up to "all those that armed forces need at the moment” across the Eastern European country.

Ukraine has been gripped by unrest since November , when ousted President Viktor Yanukovych refrained from signing an Association Agreement with the European Union in favor of closer ties with Russia. The Ukrainian parliament removed Yanukovych from power last week and named Oleksandr Turchynov, the legislature’s speaker, as the country’s interim president.