The Ukrainian authorities have appealed to the UN to convene a Security Council session as soon as possible to address the situation in Ukraine.

"We are addressing our partners at the UN Security Council to immediately convene a UN Security Council session. We will present evidence proving that attempts to escalate the conflict […] and disrupt the presidential elections have been made on the part of Russia," Ukrainian Prime Minister Arseniy Yatseniuk told journalists in the Kyiv region on Thursday.

In commenting on Russia's assurances that its troops, which recently conducted exercises near the Ukrainian border, are being pulled back to their permanent bases, Yatseniuk branded them as "bluffing."

He said also that the Ukrainian Foreign Ministry had forwarded a note to Russia accusing it of fuelling the conflict.

Yatseniuk also said he was sure that nothing would prevent the organization of presidential elections in Ukraine on May 25. "The elections will be held. Our armed forces and the Ukrainian army are ensuring law and order. War has been declared on Ukraine. We have picked up this gauntlet, and any attempts to disrupt presidential elections and seize Ukrainian territory are and will be in vain," he said.

The Ukrainian Foreign Ministry circulated a statement on attempts to disrupt the presidential elections on May 25 in Kyiv on Thursday. "The Ukrainian Foreign Ministry expresses its resolute protest against attempts to illegally cross the Ukrainian border from Russian territory, which have been committed with the authorities' and border guards' connivance," it said.

Kyiv views the situation at the border as "attempts to disrupt the organization of presidential elections on May 25 and destabilize the situation in the eastern regions of our country."