The OSCE appealed to Russia on Jan. 27, 2015 to close its border with Ukraine to help reduce conflict in the embattled border region. Photo by CIA World FactBook

VIENNA, Jan. 27 (UPI) -- The Organization for Security and Cooperation in Europe has appealed to Russia to close its border with Ukraine in order to contain conflict in the border region.

"Russian leaders have spoken of their support for a peaceful resolution to the conflict in Ukraine," OSCE Parliamentary Assembly President Ilkka Kanerva noted Tuesday.


"In keeping with that pledge, I call on Russia to close the border to halt the flow of any weapons or fighters -- whether volunteers or not -- which may be entering eastern Ukraine. The advanced weaponry that is being employed by the illegal separatists in Ukraine is not appearing out of thin air," Kanerva said.

The appeal follows a "grave escalation" in violence in eastern Ukraine, the OSCE official said, referring to a deadly attack by pro-Russian rebels on civilian neighborhoods in Mariupol that left 30 dead and 95 wounded.

Following the assault on the strategic port city of Mariupol, U.S. Secretary of State John Kerry called on Russia to close its border with Ukraine and halt the flow of weapons and money to fighters. "Otherwise," he warned, "U.S. and international pressure on Russia and its proxies will only increase."

The deteriorating security situation has prompted international organizations, including the OSCE, NATO and the United Nations, to convene emergency meetings.

Ukraine's Parliament on Tuesday designated Russia "an aggressor state" and called on the international community to punish Russia for its "crimes against humanity."