Twenty-seven Gabonese opposition members were stopped by police from leaving the headquarters of their leader Jean Ping, after rioting erupted over the election victory of rival President Ali Bongo, Radio France Internationale reported Friday.
A government spokesman later said they were allowed to go home.
Security forces had attacked the building early Thursday, killing two people.
Opposition representative Paul-Marie Gondjout accused the government of "sequestering" the group, which included a former vice-president and a former cabinet minister.
They were allowed to leave after French Foreign Minister Jean-Marc Ayrault expressed concern over their "difficult sanitary conditions" in the building and called for their immediate release.
Police have arrested hundreds of people after demonstrators set parliament on fire following the announcement of the election results on Wednesday.
Rioting continued Thursday, with protesters looting shops, torching buildings and clashing with police, according to RFI.
Bongo accuses the opposition of orchestrating the violence over the August 27 election, which Ping lost by a small margin. Ping accuses the government of fraud.
The election victory secured Bongo, whose Gabonese Democratic Party has a firm grip on power in the oil-rich nation, a second seven-year term.
The 57-year-old was elected for a first term in disputed 2009 polls following the death of his father Omar Bongo, who had ruled Gabon since 1967.