According to information gathered by Amnesty International, security forces opened fire at demonstrators in the cities of Thala, Kasserine and Regueb, central Tunisia, in an increasingly violent crackdown on protesters angry at existing living conditions, unemployment and corruption.
The government says police opened fire in self-defence after public buildings were attacked during the protests, which continued on Monday.
According to reports received by Amnesty International, security officers used tear gas and live ammunition to disperse crowds. The organization has received further reports of killings of protesters in Kasserine on Monday.
"The authorities must urgently ensure the safety of protesters and instruct security forces to act with restraint and not to use excessive force against them," said Hassiba Hadj Sahraoui, Amnesty International’s Middle East and North Africa Deputy Director.
“The authorities claim they acted in self-defence but the rising death toll and the images of demonstrations suppressed by the security forces cast serious doubt on this version of events.”
The death toll was reportedly highest in Kasserine, where Amnesty International has recorded 13 people killed in two days.
Four protesters were reportedly shot dead in Kasserine on Saturday. Then on Sunday, according to testimonies collected by Amnesty International, security officers opened fire on demonstrators who had gathered for the funerals of a 17-year-old boy who had been killed the previous day, leading to the death of a further nine people.
In a separate incident, at least five people were reportedly killed in Thala on Saturday, while five more were shot dead in Regueb, with many more injured. Amnesty International fears that the actual death toll might be higher as the fate of missing people becomes clearer.
"It is essential that authorities disclose the instructions that are being given to officers in response to the protests, instructions which should be aimed at preserving human life," said Hassiba Hadj Sahraoui.
"The authorities need to immediately launch thorough and impartial investigations into the deaths that have occurred, and those found responsible for committing or ordering excessive use of force must be held responsible."
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.
While many demonstrations started as non-violent, in some cases violence erupted, including stone throwing and acts of arson on government buildings.
Mohamed Bouazizi's death has also sparked a series of attempted suicides, several of which have been successful.
Scores have reportedly been detained in the protests with authorities carrying out mass arrests and night raids. Among those targeted are lawyers, journalists, students and bloggers.
The Tunisian authorities have sought to establish a media blackout on the protests, blocking internet access and closing email accounts of online activists.
At least three bloggers are known to have been arrested: Hamadi Kloucha, Slim Amamou and Azyz Amamy, whose blog and Facebook page have been deactivated since he covered the clashes in Sidi Bouzid. A rapper, Hamada Ben-Amor - known as “El General” - was arrested at the same time but was released on Sunday.
“The Tunisian authorities cannot thwart the emerging evidence of intimidation and violence being used against those merely exercising their right to freedom of expression.
"The authorities must immediately release those detained solely for trying to speak out, including the three bloggers," said Hassiba Hadj Sahraoui.
International standards require that firearms are not used unless strictly unavoidable, and then only in order to protect life. Law enforcement personnel must exercise restraint, minimize damage or injury and respect and preserve human life.