BRUSSELS NATO Secretary-General Anders Fogh Rasmussen said on Friday a planned referendum in Ukraine's Crimea region would violate international law and lack legitimacy.
Moscow shipped more troops and armor into Crimea on Friday and repeated its threat to invade other parts of Ukraine in response to violence in Donetsk on Thursday night, showing no sign of bowing to Western demands to pull back.
Crimea's parliament has voted to join Russia and has set a referendum on the decision for Sunday.
"The so-called referendum ... would be a direct violation of the Ukrainian constitution and international law. If held, it would have no legal effect or political legitimacy," Rasmussen said in a statement.
"Holding this referendum would undermine international efforts to find a peaceful and political solution to the crisis in Ukraine," he said.
Rasmussen issued the statement after ambassadors from Russia and Ukraine took part in a 50-nation meeting at NATO headquarters to discuss the crisis.
Ukraine asked for the extraordinary meeting of the Euro-Atlantic Partnership Council, a forum that includes the 28 NATO allies and 22 other countries from Europe and central Asia.
Rasmussen urged Russia to act responsibly and to uphold its obligations under international law.
"Dialogue and negotiations should be given a chance to succeed in bringing about a de-escalation of the situation and a political solution," he said.
A NATO official said the overwhelming majority of countries represented at the meeting expressed solidarity with Ukraine and support for Ukraine's territorial integrity and sovereignty.
Moscow's Ambassador to NATO, Alexander Grushko, defended Russia's actions, the official said.