The estimates are ten times higher than the officially released death toll figures. The official data is clearly too low, German intelligence sources told a Frankfurt-based newspaper, Frankfurter Allgemeine Sonntagszeitung.
Speaking at a Munich Security Conference on Saturday, Ukrainian President Poroshenko said that 1,200 combatants and 5,400 civilians have been killed during the conflict.
The September 2014 Minsk agreements envisaged a ceasefire between Kiev and pro-independence fighters in southeastern Ukraine, an all-for-all prisoner exchange and the withdrawal of heavy weaponry along the line of contact.
According to the Office of the UN High Commissioner for Human Rights, the recent uptick in fighting has seen casualty figures spike, with 224 civilians killed and 545 wounded in the three weeks leading up to February 1.
Several outspoken US Senators have repeatedly called for the provision of lethal assistance to Kiev, while a number of European states, including Finland, France and Italy, have opposed this option.
Speaking in Munich, Russia's Foreign Minister said that the plans of the United States to supply weapons to Kiev may disrupt the settlement of the Ukrainian conflict.
"Plans to supply military equipment and weapons to Kiev, that are being discussed in Washington, are fraught with unpredictable consequences and bear a threat of disrupting the efforts of political settlement of the conflict in the southeast of the country," the Russian foreign minister said.
Meanwhile, US Senator John McCain has criticized German Chancellor Merkel for not agreeing to supply lethal arms to Ukraine..