Police and protesters clashed in the centre of the Tunisian capital Wednesday, bringing unrest to the government's doorstep after nearly a month of violent protests that pose the most serious challenge to the autocratic president's two decades of iron-fisted rule.

Police fired tear gas at hundreds of protesters at a main intersection, driving them to disperse into adjoining streets. It was not immediately clear whether there were any injuries or arrests.

Two army vehicles were posted at the intersection, which is right by the French Embassy.

The fighting erupted hours after the interior minister was fired, a move that intensified a sense of uncertainty and questions about what's next for autocratic President Zine Al- Abidine Ben Ali  -- questions that have never been openly posed during his time in power.

The protests over Tunisia's soaring unemployment and corruption erupted after a young man tried to kill himself. They spread as social networks like Facebook spread word of the unrest despite tight control of the media.

Police have repeatedly shot at demonstrators setting fire to buildings and stoning police. The government says 23 people have died but unions and witnesses put the toll at 46 or higher.