UNITED NATIONS (AP) -- The U.S. ambassador to the United Nations on Thursday accused Moscow of having "outright lied" about its role in Ukraine, as alarmed members of the Security Council demanded that Russia remove its fighters from a new front in the unfolding crisis and threatened sanctions.
A top U.N. official told the emergency meeting that the spread of violence in southeastern Ukraine marked a dangerous escalation, but that the international body had no way of independently verifying the latest reports of Russia sending in troops and tanks.
The meeting came hours after a top Ukrainian official said two columns of Russian tanks and military vehicles fired missiles at a Ukraine border post, then rolled into the country.
U.S. Ambassador Samantha Power said the council was meeting for the 24th time on Ukraine and the fighting between pro-Russia separatists and the new Ukrainian government.
"Every single one has sent a straightforward, unified message: 'Russia, stop this conflict. Russia is not listening,'" she said, adding that Russia's force along the border with Ukraine is the largest it's been since it started deploying there in late May.
Russia "has manipulated. It has obfuscated. It has outright lied," Power said. She said the U.S. will work with its G7 and European partners "to ratchet up the consequences on Russia." France also warned of increased sanctions if the escalation continues.
Russian Ambassador Vitaly Churkin offered a spirited defense, saying Kiev "is waging war against its own people."
Churkin did deny not the presence of Russian fighters.
"There are Russian volunteers in eastern parts of Ukraine. No one is hiding that," he said. But he questioned the presence of Western advisers in the country and asked where Ukrainian troops were getting weapons.
Churkin said he wanted to "send a message to Washington: Stop interfering in the internal affairs of sovereign states."
Moscow has been virtually isolated in the Security Council meetings on the Ukrainian crisis, but because of Russia's veto power as one of the council's five permanent members, the body has been unable to act.
Statements from NATO, Ukrainian President Petro Poroshenko, the separatists, the United States and the president of the Security Council on Thursday left no doubt that Russia had crossed the border into Ukraine. The various statements cited internal reports, satellite imagery of armored vehicles and even photographs from Russian troops, including one by a soldier who showed himself operating military hardware.
As of Thursday, the separatist arsenal included up to 100 tanks, 80 armored personnel carriers, 500 anti-tank weapons and more than 100 artillery pieces, said British Ambassador Mark Lyall Grant, the council president this month. Russia has directly supplied almost all of this equipment, Lyall Grant said.
"Now we see irrefutable evidence of regular Russian forces operating inside Ukraine," he said.
The new southeastern front raised fears that the separatists are seeking to create a land link between Russia and Crimea, which Russia annexed in March.
U.N. Undersecretary-General of Political Affairs Jeffrey Feltman told council members that the U.N. could not verify on its own the latest reports of Russian troops inside Ukraine.
Ukraine's deputy ambassador to the U.N., Oleksandr Pavlichenko, wondered aloud if the world will ignore the apparent invasion or act.
"How many more red lines have to be crossed before this challenge can be addressed?" Pavlichenko asked the council.
As the final council member spoke, the German mission to the U.N. tweeted, "All but one #UNSC members condemn recent military escalation, call for restraint. Just one member has very different narrative."
Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.