REUTERS/Kevin Lamarque
German officials in Brussels have also briefed that Berlin favors a time limit on how long new Russian sanctions should last to provide an opportunity for relations to return to normal, the source said.
EU ambassadors will discuss for the first time on Thursday imposing sanctions on sectors of the Russian economy, known in EU jargon as "stage three" of sanctions.
German officials said "the transition to stage three of sanctions should follow seamlessly and can be expected by the end of the month," the source said.
(Reporting by Barbara Lewis, editing by Adrian Croft)