Security forces in the Tunisian capital have fired tear gas into crowds of protesters outside the interior ministry.
The demonstration comes a day after police cleared protesters from the streets demanding the resignation of the interim prime minister, Mohammed Ghannouchi.
Although Ghannouchi has introduced some reforms, protesters remain angry that figures from the authoritarian government of ousted President Zine al-Abidine Ben Ali remain in place. Ghannouchi, who had served under Ben Ali, has promised elections by mid-July.
Reuters reports that the youths targeted in Saturday's protest were loyalists of Ben Ali. "These are Ben Ali's thugs," a police officer told the news agency.
Crime rates have soared since the Jasmine Revolution with security officials claiming the deposed president's supporters are trying to destabilise the country, Reuters added.