The broadcaster said that Ibraheema Yakubu, assigned to cover a rally on June 23rd in the north-western city of Kaduna, "was taken into police custody and beaten by officers of the police force".
"Police officers beat him apparently to discredit him by obtaining a forced confession that he belonged to the Shiite group of the protesters," said the broadcaster.
Deutsche Welle said Yakubu's equipment was also damaged by police, calling his treatment "completely unacceptable".
"We are asking you to take the necessary steps to hold the police officers involved accountable," said the broadcaster in its letter to the Nigerian authorities.
"Also, we demand that the release on bail of our correspondent be rescinded immediately and that all charges against him shall be dropped," it added.