Fifteen unidentified gunmen have stormed into a privately owned Gabon television station's building before burning down its analogue signal systems, an official has said.

The attack targeted independent television station TV+ in Libreville yesterday, and has been roundly condemned as "barbaric" and "cowardice" by officials in the country.

As a result of the sabotage, all transmission technologies comprising modulation, demodulation, line coding and equalisation have been destroyed thereby forcing the independent television not to broadcast.

This has been the second attack on the broadcaster since 2009.

TV+ director-general, Frank Nguema, has expressed grave concern over the burning of the sole independent television station in Gabon.

"We have since reported the matter to the police. We don't really who these attackers are. Their motive is not known either," said Nguema.

Nguema said the unidentified men were armed with assault rifles and pistols when they subdued the 5 security guards at TV+ around 1 am local time. They then set fire to the station's transmitters on the third floor of its building.

Hours before the attack, TV+, owned by former Interior Minister André Mba Obame, had extensively covered violent clashes between security forces and Obame's supporters, who are calling for the ouster of President Ali Bongo and the holding of a national conference to draft a new constitution, news reports said.

As a result of the attack, the privately owned television is not broadcasting citing destruction of transmission network technologies.

Commenting about the barbaric attack on the sole independent television channel in Gabon,  Committee to Protect Journalists (CPJ) Africa advocacy Coordinator, Mohamed Keita, said the act was political "thuggery" and "censorship".

"We condemn the armed attack on TV+ and the sabotage of its transmitters as an act of political thuggery and censorship against an outlet critical of the government.

"The Gabonese government must carry out a credible and transparent investigation or risk being suspected of involvement in the attack," said Keita.