Guilherme Portanova of Globo TV was held for about 40 hours by the First Capital Command gang, before being driven in the trunk of a car to a neighborhood several kilometres from the TV station's offices and set free on Monday.

The release of Portanova, 30, came after Globo broadcast a video with the gang calling for improvements in Brazil's prison system.

Portanova and his technician, Alexandre Coelho Calado, were kidnapped near Globo's offices in Sao Paulo on Saturday morning by armed men, and Calado was subsequently released earlier along with the video.

Authorities believe that the First Capital Command, or PCC as it is known, a gang based in overcrowded and loosely controlled prisons, is behind the three waves of attacks against police and civilian targets that have killed more than 200 people since May.

Portanova had worked on news reports about the attacks for Globo.