A South Korean hip-hop duo were arrested and released by US military police in central Seoul after they shot a music video for their new album without permission from the authorities, local police said Thursday.

Mighty Mouth, a male duet made up of rappers Shorry J and Sangchu, was apprehended by the US military police of the 8th Army late Wednesday, according to the Yonsan Police Station. 

Two other staff members, including the director whose identity was withheld, were also arrested on-site. They were all sent to the Yonsan precinct and questioned by the police overnight before they were released, the local police said.

They said they only booked the two staff member on charges of entering the protection zone in the camp in violation of a law regarding military facilities. The two rappers were sent home without being booked as they were not responsible for making arrangements for shooting venues, the police said.

The police plan to talk to military officials in the US base to determine if the incident needs to be further investigated as a formal case. They all reportedly had visitors' passes on them but never obtained permission from the US military for the filming.

The authorities said that any filming of the base or facilities in the camp is strictly subject to approval from the commanding officer.

Mighty Mouth debuted in 2008 and their album "Energy" featured a number of well-known female singers, including Yoon Eun-hye and Sunye, a former member of the Wonder Girls. (Yonhap)