German Foreign Minister Frank-Walter Steinmeier says that the situation in eastern Ukraine is deteriorating and that all sides, including Russia, must adhere to a cease-fire and steps toward peace agreed in the Belarusian capital, Minsk, on September 5.
Steinmeier was speaking in the Kazakh capital on November 10, a day after the European Union and the United States voiced deep concern over reports of large convoys of troops and military vehicles moving through territory controlled by pro-Russian rebels.
"Unfortunately, the situation is again serious. I now think that we must call upon all those involved in this conflict, as well as the Russian side, to return again to the terms of the Minsk protocol," Steinmeier told a news conference in Astana.
The Western statements adds to pressure on Russian President Vladimir Putin, who denies Moscow has lent military support to separatists fighting to carve out states in eastern Ukraine in a conflict that has killed more than 4,000 people since April.
Some of the most intense shelling since the cease-fire occurred in the Donetsk province on November 9, fueling fears of an escalation following November 2 votes -- denounced by Kyiv and the West but "respected" by Russia -- in which the separatists elected leaders of two self-proclaimed "people's republics."
On November 8, the Organization for Security and Cooperation in Europe (OSCE) said its monitors had spotted an armored column of troops without insignia heading west on a highway near Donetsk, one of two separatist-controlled provincial capitals in eastern Ukraine.
Ukraine, which had accused Russia of sending a column of 32 tanks and truckloads of troops into eastern Ukraine, said on November 9 that it had no doubt the new troops were Russians.
More reports of other military convoys with unmarked vehicles, weapons, and troops emerged on November 9 and 10.
Ukrainian military spokesman Andriy Lysenko said the conflict had intensified in the past week and that Kyiv believes Russia could stir up tension to provide a pretext to "send in so-called Russian peacekeeping units."
In Washington, National Security Council spokeswoman Bernadette Meehan said the White House was "very concerned" by the intensified fighting and reports of the separatists moving large convoys of weapons and tanks to the front lines.
"Any attempt by separatist forces to seize additional territory in eastern Ukraine would be a blatant violation of the Minsk agreements," Meehan said.
She also urged Russia to stop arming the rebels and withdraw all its troops and weapons from Ukraine.
EU foreign policy chief Federica Mogherini called the reports of rebel convoys "a very worrying development."
Demanding all parties adhere to the September 5 cease-fire and seek a solution that would respect Ukraine's territorial integrity, Mogherini urged Russia to "fully assume its responsibilities in this regard."
That means "preventing any further movement of military, weapons or fighters from its territory into Ukraine, and withdrawing any troops, weapons and equipment under its control from Ukraine," she said.
Russian Foreign Minister Sergei Lavrov said on November 8 that he had "no information" about Russian troops or tanks being in eastern Ukraine.
A rebel commander has also denied Moscow has sent fresh arms or troops.
Eduard Basurin, a rebel commander in Donetsk, said the separatists were only moving fresh fighters to the front line.
"We have to rotate some of our formations," Basurin told state-run Russian news agency RIA Novosti.
With reporting by AP, Reuters, AFP, and dpa