Germany has rejected North Korea's top envoy nominee to Berlin, a U.S.-based media outlet report said Thursday.

Radio Free Asia said the German government recently rejected the North Korean government's request for Berlin's approval for its new ambassador nominee who was set to replace incumbent Ambassador Ri Si-hong.

The exact reason behind the German government's decision is still unclear, although observers have speculated it may be due to concerted moves by countries around the world to keep better tabs on North Korean diplomats who may have been involved in unlawful activities in the past.

The media outlets said that because of Germany's move, Ri returned to Berlin from Pyongyang and resumed his ambassadorial duties.

The RFA reported that sources in Berlin hinted that Ri may have been recalled initially for failing to meet expectations. It said the fact that Pyongyang had to send back a diplomat it recalled shows the difficult situation the country finds itself.

The German foreign ministry previously said Ambassador Ri left Berlin in late April. Ri was appointed ambassador to Berlin in June 2011.

It also made clear that it has a policy to not discuss whether or not it has rejected a nominee for ambassador. (Yonhap)