German Chancellor Angela Merkel says that the European Union sees no progress to justify rolling back sanctions against Russia.

"We have not enough progress in order to remove the sanctions," Merkel said. "But we all agree that we must do everything to move on with the Minsk process," she told journalists at the end of the first day of the EU summit, which began on December 14.

"We have prevented an escalation [in the east of Ukraine]," she added.

Earlier, President of the European Council Donald Tusk said the EU leaders had agreed to prolong economic sanctions against Russia for another six months.

"EU united on roll-over of economic sanctions on Russia," he tweeted on Thursday evening.