Gabon security forces fired tear gas at hundreds of anti-government protesters in the capital today, witnesses said, two days after an opposition leader declared himself president.

The usually sleepy central African oil exporter has been troubled since a 2009 election won by Ali Bongo Odimba, but which the main opposition group - inspired by power struggles in Tunisia and Ivory Coast - is insisting was rigged.

Hundreds of supporters of opposition leader Andre Mba Obame, who declared himself president on Tuesday and formed a rival government, have gathered outside the local United Nations offices to demand recognition of Mba Obame as president.

Security forces clashed with the group early today, firing tear gas into the crowd and injuring dozens, but failed to disperse them, according to several of the protesters.

Police officials were not immediately available.

Gabon authorities also suspended television broadcaster TV+, owned by Mba Obame, after it aired his swearing-in ceremony, according to a statement read over state radio.

The African Union said today it was concerned by the situation in Gabon and a growing trend of elections and governance crises across Africa.

"The President of the Commission, Jean Ping, calls on all political actors in Gabon (...) to exercise restraint," it said in a release, adding Mba Obame's self-declaration as president threatened peace and stability.

"The President of the Commission, who is worried by the trend across the continent of crises tied to elections issues and governance, expressed hope Gabon's leaders and its people will have the wisdom find the way to progress," it added.

Mba Obame this week cited Ivory Coast and Tunisia during a rally, saying "history was on the march".

Ivory Coast incumbent Laurent Gbagbo has refused to step down despite UN-certified results showing a November 28th poll was won by Alassane Ouattara and Outtara has since declared himself president.

An uprising in Tunisia this month led to the toppling of former leader Zine al-Abidine Ben Ali, and demonstrators want a purge of former regime loyalists in an interim government.

In a sign that leaders elsewhere in Africa were watching events in Tunisia closely, Senegal's president Abdoulaye Wade said he did not expect to suffer the same fate as Ben Ali as protests over chronic power cuts there grew.

"There are wicked, jealous and hypocritical people who wish and pray that what happened in some countries like Tunisia will happen in Senegal. But my marabouts are stronger than their marabouts," he said this week, referring to religious leaders in the region believed to have supernatural powers.

Bongo's election in 2009 allowed him to take over from his father Omar and led to days of rioting across the country as opponents accused him of vote-rigging.

Final results put Bongo first with 41.79 per cent, veteran opposition figure Pierre Mamboundou second with 25.66 per cent and Mba Obame third with 25.33 per cent.

Reuters