The Tunisian government has imposed a night-time curfew in the capital, Tunis, and surrounding regions.

突尼斯政府对首都突尼斯及其周边地区实行宵禁政策。

It comes after violent protests in several districts of the capital, with riot police firing tear gas at demonstrators.

Officials say at least 23 people have died across the country since the unrest began late last year.

The protesters say they are angry about rising food and fuel prices, high unemployment and corruption¹.

Human rights and trade union activists² believe the number of dead to be at least 50.

Earlier on Wednesday, President Zine El Abidine Ben Ali dismissed his interior minister in an attempt to stem（阻止） the unrest.

Rafik Belhaj Kacem had been responsible for the police force, which many people say has used excessive force against protesters.

But the BBC's Adam Mynott in Tunis says the president's efforts appear not to have worked.

At least two people were reported to have been shot dead by police in the southern city of Douz on Wednesday. One man was also reported to have been killed during clashes in Thala.

Tear gas

The interior ministry³ said the nightly Tunis curfew（宵禁） would begin on Wednesday at 2000 local time (1900 GMT) and end each day at 0600.

It said the action was being taken because of "disturbances⁴（干扰，失调） , pillaging⁵（抢劫） and attacks against people and property which have occurred in some districts of the city".

Our correspondent says the city's streets, which are normally thronging⁶ with tourists and locals until late into the evening, were ominously⁷ quiet on Wednesday night.

Violence broke out on Wednesday afternoon, as protesters threw stones and police responded with volleys of tear gas.

It is the first time in the weeks of unrest that the violence has reached the capital.

The government says 21 people died over the weekend during violence in and around the central town of Kasserine.

At a news conference on Tuesday, Communications Minister Samir Laabidi denied that police had killed any of the protesters.

He said the deaths had occurred "during attacks and acts of vandalism（破坏行为） against public buildings, police stations or schools".

Mr Laabidi accused "religious extremist movements and extremist movements from the left" of fomenting⁸（煽动，挑起） the unrest.

On Wednesday morning, the leader of the banned Tunisian Workers' Communist Party (POCT) - a prominent critic of the president - was arrested, his family and rights groups said.

Hamma Hammami had in recent days said the unrest could bring about the government's collapse⁹, calling for Mr Ben Ali to stand down.