Deutsche Telekom is seeking €1m ($1.3m) in damages from its ex-chairman and looks set make a similar claim against its former chief executive over their roles in a year-old scandal involving allegations of snooping at the telecoms group.

Deutsche Telekom’s executive board sent a letter to Klaus Zumwinkel outlining the group’s claim to “around €1m” in damages for allegedly failing to comply with his responsibilities when he was chairman, a person close to the matter said.