Greece and Malta expressed concern about the move at a meeting of EU ambassadors on Monday where the new sanctions were presented.
Countries expressed concern that the proposal could affect Europe’s shipping industry and energy prices, the sources said.
The two countries also asked for clarification on proposals to impose sanctions on foreign ports for transshipment of Russian oil and to step up monitoring of ship sellers to reduce the number of ships entering the Russian fleet.
A Greek government spokesman declined to comment.
Malta’s government spokesman in Brussels, Nestor Laivera, said the country was “involved in technical discussions to ensure that the final result can be implemented”.
Last week, the European Commission proposed to replace the current price ceiling on the sale of Russian oil with a ban on the provision of services necessary to transport it.
This proposal is the centerpiece of the EU’s 20th sanctions package.
EU sanctions require the support of all member states to be approved and are subject to change before they are adopted.
The EU plans to complete work on the new sanctions package by the end of February.