(CNN) -- Tunisian police have arrested more than 770 people since anti-austerity protests broke out this week in the North African country, according to state media and the UN human rights office.
Tunisia's Interior Ministry told state media Friday that at least 773 people had been detained, while the Office of the UN High Commissioner for Human Rights put the number arrested at 778 since demonstrations began Monday.
Protesters face various charges, including vandalism, looting, attacks against public property and causing fires and road blocks, Interior Ministry spokesman Col. Major Khelifa Chibani told state news agency TAP.
More than 85% of the people arrested are teenagers and young adults between ages 15 and 30, the news agency said.
According to Chibani, 97 police officers have been injured and 88 police vehicles damaged since protests broke out, TAP reported. Several police stations have been set on fire.
Incidents of vandalism dropped sharply on Thursday night, Chibani said.
Protesters marched peacefully Saturday in the city of Sidi Bouzid against the government's austerity measures, TAP reported. On Friday, scores of students and activists joined a rally in the capital, Tunis, the news agency said, at which they demanded the release of protesters who have been taken into custody.
The UN human rights office expressed concern Friday over the large number of people arrested; it said about 200 of them are between 15 and 20 years old.
In a written statement, Rupert Colville, spokesman for the Office of the UN High Commissioner for Human Rights, said authorities must ensure that people are not arrested in an arbitrary manner and that their rights are respected.
"We are closely watching the demonstrations across Tunisia and the authorities' response to them," he said. "The authorities must ensure that those exercising their rights to freedom of expression and peaceful assembly are not prevented from doing so."
Colville also urged those taking to the streets to exercise restraint and remain calm.
The protests have broken out in response to an unpopular new Finance Act, which saw price hikes and value added tax increases imposed from January 1. They come at a time when Tunisia's economy is struggling and many people are suffering real hardship.
The International Monetary Fund agreed in 2016 to a four-year loan program worth about $2.8 billion, but payments are tied to the Tunisian government carrying out economic and social reforms.
An anti-austerity youth movement -- named Fech Nestannow, which translates as "What are we waiting for?" -- has sprung up since the start of the year and is seeking to rally opposition to the measures.
Protests are common in Tunisia during January when many mark the anniversary of the 2011 toppling of the longtime autocratic leader, President Zine el Abidine Ben Ali.
CNN's Shelby Rose contributed to this report.
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