Their names will be made public when the updated blacklist comes into force in the next few days, the source said.
On November 17, the foreign affairs ministers of the European Union ordered EU bodies to add more independence supporters from eastern Ukraine to the bloc's sanctions list by the end of the month.
Over the past few months, the European Union, the United States and a number of their allies have imposed several rounds of sanctions targeting Russia's banking, energy and defense sectors, as well as a number of senior Russian lawmakers over Moscowэs alleged role in the escalation of the Ukrainian crisis.
The leaders of the Luhansk and Donetsk People's Republics were also subjected to EU travel bans and asset freezes. At the moment the EU sanctions list consists of 119 individuals and 23 entities.
On Wednesday, German Chancellor Angela Merkel said Western sanctions against Russia will not be lifted while the situation in Donbas remains tense.