Scores have been killed in protests over living conditions, unemployment and corruption which sometimes turned violent.
During his speech yesterday President Ben Ali blamed the violence on "hooded gangs" and the protests on "a minority of detractors who feel offended, anxious and outraged to see Tunisia achieve success, growth and progress".
According to reports received by Amnesty International, police have violently dispersed a demonstration in Tunis today organized by opposition members calling for accountability of the killings of at least 23 demonstrators over the weekend. Demonstrators included prominent lawyers and artists.
Amnesty International has also received reports of arrests across the country. The exact number of people held and their place of detention remain unclear. Some are believed to be in the premises of the Ministry of Interior.
"President Ben Ali's remarks appear to be an attempt to identify scapegoats for the many deaths and injuries that have occurred during the protests, and as such they could result in many arbitrary arrests," said Hassiba Hadj Sahraoui, Amnesty International's Deputy Director for the Middle East and North Africa Programme.
"If it is true that those arrested are responsible for acts of violence, then they must be charged with recognizably criminal offences. The Tunisian authorities must either press charges against those detained and try them in fair proceedings or release them."
Tunisia has a long record of using arbitrary arrests and detentions, with suspects held incommunicado and subjected to torture and other ill-treatment, and enforced disappearance.
Scores have reportedly been detained in the protests with authorities carrying out mass arrests and night raids.
Protests have persisted in Tunisia since mid-December following the death of Mohamed Bouazizi, a 26-year-old unemployed university graduate, who committed suicide in the town of Sidi Bouzid when police confiscated his fruit and vegetable cart, taking away his only source of income.
His desperate act sparked protests among Tunisians, including trade unionists, students, human rights activists and lawyers, who took to the streets demanding jobs, better living conditions and the end of corruption.