"We already started broadening our procurement base for coal late last year. And we are fully prepared for the embargo that the European Commission is imposing from August," Frank Mastiaux said during the group's annual general meeting.

EnBW in March said it received 3.6 million tonnes, or 86%, of its hard coal supply from Russia, adding it started to diversify procurement at the end of last year, while existing stockpiles will ensure supply well into 2022.

The EU plans to ban Russian coal from mid-August as part of sanctions designed to punish Russia for its invasion of Ukraine. It is also debating a crude oil embargo that would take effect in six months.

Gas, which is the most critical energy source for Europe and Germany in particular, has so far not been banned, and the bloc does not yet have plans to do so.

"Regarding gas, too, we are working hard towards a significant diversification of supply sources," Mastiaux said.

EnBW has said that 20% of the 495 terawatt hours of gas it procured last year came via direct agreements with Russian suppliers, adding those volumes would decrease from 2023 onwards.

(Reporting by Christoph Steitz, Editing by Miranda Murray and Barbara Lewis)