Correction: 12/01/2018: A previous version of this article misstated the number of people who have been killed in this year's protests.

More than 770 people have been arrested in Tunisia during nearly a week of protests against a government plan to raise taxes and prices of basic goods, according to the UN.

Rupert Colville, a spokesman for the UN human rights office, called for calm and restraint on Friday, and urged Tunisia's government to ensure freedom of peaceful assembly.

"We're concerned about the high number of arrests, some 778 people we understand have now been arrested since Monday, and around a third of those arrested were between the ages of 15 and 20 so very young," Colville told reporters in Geneva.

He urged the government to not detain protesters arbitrarily.

The protests broke out after the government's announcement of austerity measures in this year's budget, which took effect on January 1. At least one person was killed in the western city of Tebourba on Monday and scores more injured as violence flared in some areas.

Protesters torched government buildings, looted shops and blocked roads, prompting the army to deploy some 2,100 troops to different parts of the country.

Khelifa Chibani, a spokesman for the interior ministry, told Tunisia's press agency TAP on Friday that the protests appeared to be subsiding.

At least 151 people were arrested on charges of vandalism and looting on Thursday, he was quoted as saying by TAP.

Scores of students and activists from the group #Fech_Nestannew (What are we waiting for?) continued the protest in Tunis on Friday, according to TAP. They waved yellow cards, and demanded the government reverse austerity measures, TAP said.

Al Jazeera's Hashem Ahelbarra, reporting from the capital Tunis, said people on the streets were enthusiastic about the movement's momentum.

"People here say that they want to continue to take to the streets in order to put more pressure on the government to scrap the austerity measures," he said.

"They also blame the government for breaking the pledges it made about improving the life standards in the country as poverty and high unemployment continue."

The radio station Mosaique reported a rally in the coastal city of Sfax.

Tunisia hiked prices for fuel and some consumer goods, while taxes on items such as cars, phone calls, internet and hotel accommodation have also increased.

The government defends the measures as necessary to limit a budget deficit that hit six percent of the country's gross domestic product (GDP).

Tunisia's main opposition Popular Front has meanwhile called for demonstrations through the week.

Protests are expected to continue through January 14, the anniversary marking the removal of Zine El Abidine Ben Ali, the country's former president.

Six years since the 2011 uprising that overthrew Ben Ali, Tunisia has been held up as a model for avoiding the violence that has affected other nations after their Arab Spring revolts.

But Tunisia's economy has struggled since the revolution, with growth remaining slow.