Telstra's head of retail, Karsten Wildberger, has resigned just weeks after taking over the role.

Telstra has cited ‘personal reasons' for the resignation, saying Wildberger plans to return to Germany towards the middle of next year.

No replacement for Wilderberger has been announced.

Andrew Penn, Telstra chief executive, says Wildberger has contributed to Telstra's progress since joining the company in 2013, first as GMD consumer and then assuming accountability as GMD products, before being appointed as Retail group executive in October.

“We will be disappointed to see him go, but understand his personal reasons,” Penn says. “Karsten brings great energy and passion to our business and has significant global experience.

Wildberger says he has ‘thoroughly enjoyed' his time with Telstra and in Australia.

He will take on an executive role outside of the telecommunications industry on his return to Germany.