Tunisia on Friday declared a nighttime curfew across the country after a wave of protests and clashes that constitute the most serious outbreak of social unrest since its 2011 revolution.

Five years after the overthrow of longtime dictator Zine El Abidine Ben Ali, street demonstrations against unemployment and poverty are again shaking the North African nation.

Fourteen people were slightly wounded Tuesday in the central Tunisian city of Kasserine when police fired tear gas to disperse hundreds of demonstrators demanding jobs, officials said.

Authorities later imposed a curfew on the impoverished city, where tensions have been high since Saturday when a young unemployed man suffered a fatal electric shock during a protest.

Thousands gathered in the Tunisian capital Thursday to mark the fifth anniversary of the overthrow of longtime dictator Zine El Abidine Ben Ali in the uprising that inspired the Arab Spring.

Tunisians thronged Habib Bourguiba Avenue, the main thoroughfare in central Tunis and the epicenter of the country's revolution five years ago.

Tunisia extended for another two months Tuesday a state of emergency imposed after a deadly November bus bombing claimed by the Islamic State group, the presidency said.

President Beji Caid Essebsi has "decided on an extension of the state of emergency over all the territory" of the country "until February 21, 2016," a statement said.

Tunisia has reopened its border with Libya, 15 days after it shut the frontier following a suicide bombing in Tunis claimed by the Islamic State jihadist group, the interior ministry said Friday.

"The border with Libya was opened Thursday at midnight," ministry spokesman Walid Louguini told AFP.

The Nobel Peace Prize was on Thursday presented to a group of four organizations that saved Tunisia's transition to democracy through dialogue, a method the laureates are keen to see applied in Syria and Libya.

"This year's prize is truly a prize for peace, awarded against a backdrop of unrest and war," the head of the Norwegian Nobel Committee Kaci Kullmann Five said at the formal award ceremony in Oslo, held in the presence of Norway's King Harald and under tight security amid the threat of a jihadist attack.

The Tunisian government on Tuesday shortened a nighttime curfew imposed in the capital after a deadly November bus bombing claimed by the Islamic State group.

The curfew will now start at midnight instead of 9:00 pm, allowing some respite for Tunis shopkeepers and cafe owners who had felt the pinch from the loss of business in a city of more than one million people that usually bustles at night.

Tunisia has identified three suspects wanted over Tuesday's suicide bombing that killed 12 presidential guards and is offering a financial reward for information leading to their arrest.

The interior ministry issued a statement on Friday evening identifying the wanted men as Hassan Ben Khalifa Bouchiba, Houcine Ben Khalifa Bouchiba and Walid Ben Mohamed Ali Yousfi.

Tunisia's leaders faced calls Thursday to rethink their strategy in the fight against extremism following a suicide bombing by the Islamic State jihadist group of a busload of presidential guards.

The North African nation's struggle against Islamist violence has taken on added urgency following three major attacks this year by IS, which has made Tunisia one of its main targets.

A jihadist group claimed the beheading of a young Tunisian shepherd on behalf of Islamic State, accusing him of having informed the army about their movements in the central province of Sidi Bouzid, in a video posted on the Internet Sunday.

The killing of 16-year-old Mabrouk Soltani on November 13 sparked anger in Tunisia. His killers ordered a 14-year-old who was working with him to bring the victim's head wrapped in plastic to his family.