President Moncef Marzouki on Wednesday swore in a new government to pull Tunisia out of its political and economic crisis, urging patience and saying there was no "magic wand" to solve the country's problems.

The oath-taking by Islamist Prime Minister Ali Larayedh and his cabinet took place after lawmakers approved the new team in a vote overshadowed by the death of an impoverished young street vendor who had set himself on fire a day earlier.

"I speak to all those desperate young people, who are at the end of their patience and who see no glimmer of hope on the horizon," Marzouki said, evoking the memory of 27-year-old Adel Khazri who died from his injuries in the morning.

"We do not forget the loss of one of our children in the same way and, perhaps for the same reasons, as the martyr of our revolution," the president said.

He was referring to another young street vendor, Mohamed Bouazizi, who set himself on fire in December 2010 in a drastic act of protest against police harassment.

His self-immolation in the town of Sidi Bouzid ignited a mass uprising that ousted dictator Zine El Abidine Ben Ali the following month and touched off the Arab Spring uprisings.

"Do not despair of God's mercy, of the sympathy of the people and of the government," Marzouki added, while urging patience.

The new government does "not have a magic wand to resolve the problems of poverty and unemployment that have accumulated over three decades, but it has the unbending will to confront this tsunami of problems."

Economic and social difficulties were the key factors that brought down Ben Ali's regime, and two years after he fled to Saudi Arabia, unemployment and poverty still plague the North African country.

The economy was badly affected by the revolution, which paralysed the strategic tourism sector, although the country is out of recession and posted 3.6 percent growth in 2012.

The unemployment rate is about 17 percent, and is especially high among young graduates.

Larayedh's coalition of his own Islamist party Ennahda, two secular parties and independents received 139 votes, or 30 more than needed, in Wednesday's parliamentary session.

Just before the vote, Larayedh also commented on Khazri's death, calling it a "sad incident" and saying: "I hope we understood the message."

Witnesses quoted Khazri as shouting: "This is a young man who sells cigarettes because of unemployment," before setting himself on fire in Tunis.

Larayedh later told AFP that the country was threatened by both "terrorism" and social unrest.

"The main danger to national security is terrorism, whether it comes from abroad or from inside the country," he said, adding that another threat was "social violence fed by politics."

Officials said Khazri, from a very poor family in the northwestern Jendouba area, had arrived in the capital a few months ago to look for work.

Around 30 angry street vendors organised a demonstration Wednesday near the municipal theatre on Habib Bourguiba Avenue -- epicentre of the uprising -- where Khazri had set himself alight.

They shouted "shame on the government, the youth are burning."

Khazri's brother Issam said he is to be buried on Thursday in the northwestern town of Souk Jemaa.

-- Lack of consensus --

In addition to economic hardships, Tunisia is grappling with a political crisis exacerbated by the assassination last month of Chokri Belaid, a leftist opposition leader.

The country is still without a fixed political system because of a lack of consensus between the main parties.

Ennahda, which led the previous coalition, is pushing for a pure parliamentary system while others are demanding that the president retain key powers.

Larayedh said on Tuesday he was determined that his government would serve until year end, stressing that his priorities were to organise elections, deal with unemployment and the cost of living.

The new cabinet was formed as part of efforts to resolve the political impasse, which last month brought down the government of Hamadi Jebali.

The National Constituent Assembly is also to vote on a timetable for the adoption of a new constitution.

A proposal was submitted on Monday that the charter be adopted in July, with elections held in October, but observers are not overly confident that those dates will be met, given previous failures.