Libreville - Security forces in Gabon violently charged at demonstrators gathering on Saturday in Libreville in the lead-up to presidential elections and beat an AFP cameraman covering the protest, a colleague said.Defying a heavy police presence, hundreds of protesters took to the streets in opposition to President Ali Bongo Ondimba's candidacy for re-election on August 26, the AFP correspondent said.Some 15 opposition leaders also attended the protest, forming a human chain at the front of the crowd. Among them was presidential candidate Guy Nzouba Ndama, the former parliamentary speaker.The young protesters broke into song, chanting the national anthem as the security forces began firing teargas at the crowd.Police then moved to break up the protest and several shots were heard, according to the AFP journalist who saw 70-year-old Nzouba Ndama running for cover with other demonstrators.Armed, masked members of the security forces grabbed the AFP journalist's cameraman colleague and threw him onto a pick-up truck, even though his camera was clearly marked.Several officers beat him and then released him minutes later, along with his camera.Suffering from back pain, the cameraman went to a Libreville hospital for X-rays.AFP's Global News Director Michele Leridon expressed her "indignation and concern after this attack", adding that the agency planned to lodge a complaint with the authorities "so that journalists can do their job safely, particularly as the presidential election draws near".'Regrettable'Gabon's Information Minister Alain-Claude Bilie-By-Nze described the incident as "regrettable"."It cannot have happened on instructions from the government," he said, adding that the security forces had been trained "to protect journalists in demonstrations".He suggested that the AFP journalist was picked up because "he was among the demonstrators and wasn't wearing anything distinctive" to show he was in the media.Two members of the security forces were seriously hurt and 11 demonstrators were arrested, Bilie-By-Nze added.Another journalist covering the protest was also harassed by the security forces, who seized his camera.Nzouba Ndama told AFP that Saturday's incident "shows Ali Bongo Ondimba is afraid of the opposition speaking its mind."They have gone beyond the pale by attacking unarmed citizens."The UN under-secretary general for political affairs, Jeffrey Feltman, on Friday expressed his "deep concern over the growing tensions in the country" ahead of next month's election.Bongo's father, Omar Bongo Ondimba, ruled the central-western country, a former French colony until it gained independence in 1960, for 41 years until his death in 2009.During this time, Gabon tapped into the world's oil boom and its per-capita income rose to four times that of most sub-Saharan African nations.But relatively little of the prosperity has trickled down. Critics accuse the Bongo family of usurping the country's riches and stifling democracy.