The European Union has accused Moscow of launching a "conscription campaign" in the Russia-controlled Ukrainian region of Crimea, in a move that the bloc said violated international law.
The EU's strongly worded statement came as Ukraine accused Russia of massing troops near their shared border, an accusation rejected by the Kremlin.
"Today, the Russian Federation has launched yet another conscription campaign in the illegally-annexed Autonomous Republic of Crimea and the city of Sevastopol to draft residents of the peninsula in the Russian Federation Armed Forces," the EU said in a statement on April 1.
Observers noted that Russia has in the past conducted military call-ups in the springtime.
The bloc said the Russian military conscription drive in Crimea was "another violation of international humanitarian law."
It stressed that "the Russian Federation is bound by international law, and obliged to ensure the protection of human rights on the peninsula" and reiterated "the EU does not and will not recognize the illegal annexation" of Crimea.
Russia annexed Ukraine's Crimean Peninsula in March 2014, sending in troops and staging a referendum denounced as illegitimate by the international community after Moscow-friendly Ukrainian President Viktor Yanukovych was ousted amid a wave of public protests.
Moscow also backs separatists in a war against Ukrainian government forces that has killed more than 13,000 people in eastern Ukraine since April 2014.
The EU has imposed several rounds of sanctions on individuals and entities accused of undermining Ukraine’s territorial integrity and sovereignty.