Ukraine said it had stopped a column of Russian troops posing as “peacekeepers” traveling with a humanitarian convoy as they reached the border. Valery Chaly, deputy head of Ukraine President Petro Poroshenko’s administration, said the peacekeepers were going to Ukraine to trigger unrest and provoke further conflict.

The Russian troops were part of a convoy that was reportedly part of an agreement with the Red Cross, Reuters reported. "A humanitarian column with 'peacekeepers' was to enter the territory of Ukraine, clearly to provoke a full-scale conflict," Chaly said in a statement. Russia has denied Ukraine's claims and Maria Zakharova, a Russian Foreign Ministry spokeswoman, said Kiev "is more and more inventive in creating fairy tales."

During the week, NATO and western governments warned Russia about the number of troops amassed at the Ukraine border. NATO Wednesday said Russia moved 20,000 troops to the border, calling it a "dangerous situation." The United States voiced concern about the troops at the border, recognizing the need for humanitarian efforts to provide aid and passage for civilians in eastern Ukraine but saying Russia should not be involved in these efforts.

"Against a background of numerous violations by Russia of the border regime with Ukraine and deliveries of weapons, equipment and mercenaries, Ukraine has enough grounds for believing that this convoy can be used again for further escalation of tension," Ukraine's Foreign Ministry said in a statement.

Igor Girkin, a pro-Russian separatist commander, said Saturday Ukrainian troops surrounded Donetsk, the separatist stronghold, the Associated Press reported. Ukrainian troops have taken the town of Krasnyi Luch, which cuts off a main route between Donetsk and the rebel-controlled city of Luhansk.