"Russia violations in Ukraine to top agenda at extraordinary meet of OSCE delegations at 11:00 CET (0900 GMT) today in Vienna," the US mission said in a tweet.
The Austria-based Organisation for Security and Cooperation in Europe confirmed the special session, which "will focus on latest developments in Ukraine".
Ukraine's ambassador to the OSCE accused Russia on Thursday of a "direct invasion" following reports that Russian troops were active in the conflict-torn east of the country.
"We registered a direct invasion by the Russian military into the eastern regions of Ukraine," Ihor Prokopchuk told journalists following a special meeting of the European security body to discuss the latest developments in Ukraine.
"The situation has significantly aggravated," he said in English, citing the capture "by regular Russian forces" of the key southeastern town of Novoazovsk and several other surrounding towns.
"Ukraine views the latest developments as active aggression against Ukraine," Prokopchuk said.
There has been increasing concern in Kiev and the West that Russia is sending troops into eastern Ukraine, although Moscow has repeatedly denied the allegations.
Moscow's envoy to the OSCE denied Thursday that any Russian troops were in eastern Ukraine, after his Ukrainian counterpart accused Moscow of a "direct invasion" of its territory.
"There are no Russian soldiers" in eastern Ukraine, Andrey Kelin told journalists, following an emergency meeting of the European security body to discuss developments in Ukraine.
Washington's ambassador to Ukraine Geoffrey Pyatt earlier accused Russia of being "directly involved" in the fighting between government forces and Moscow-backed separatists in the east.
The Ukraine Today news channel reports that up to 15,000 Russian soldiers may already be deployed in Ukraine, a claim which the Russian government strenuously denies.
The US State department has confirmed that troop movements at the border strongly suggest that Russia is directly involved in a counter-offensive which is supporting the Russian-backed rebels in eastern Ukraine.
Previously, OSCE general secretary Lamberto Zannier said that finding a solution for the bloody conflict in east Ukraine is the "top priority" for the OSCE (Organisation for Security and Cooperation in Europe). He was speaking to the Austrian Press Agency (APA) on the sidelines of the Alpbach political forum in Tyrol province on Monday.
A recent meeting between Russian and Ukrainian representatives and the OSCE in Minsk was "a step forwards" said Zannier.
It was important to speed up the conflict resolution process at a political level, said the OSCE general secretary. A ceasefire was currently the priority. "The political process is the key (…)," said Zannier. "I am sure that Russia is not interested in maintaining this instability on its doorstep. The conflict in Ukraine must be resolved."
Zannier said that a military solution was unrealistic. It would be very costly, also in terms of civilians and refugees, he added.
The OSCE general secretary also warned against "aggressive nationalism," not only in Russia and Ukraine, but also in Western Europe. It caused confrontations and conflicts, he said, and people who lived in multi-ethnic societies had to struggle with intolerance.
Portions of this story came from the Austrian Press Agency (APA).