Clashes between Tunisian security forces and supporters of the hardline Islamist Ansar al-Sharia group left at least one person dead and several injured on Sunday, dpa reported.
The clashes came after hundreds of supporters of the group took to the streets to protest after authorities banned it from holding its annual congress.
The victim, an Ansar al-Sharia supporter, died in hospital, the official TAP news agency reported.
The protesters blocked streets in the capital Tunis with burning barricades and threw stones and petrol bombs. Security forces fired tear gas and rubber bullets to disperse them, witnesses said.
The Interior Ministry earlier said 11 security personnel and at least three protesters were injured.
Police detained at least 20 people, TAP reported. Authorities said around 700 people took part in the protest.
Similar clashes were reported in central city of Kairouan, where the Ansar al-Sharia meeting had been due to take place.
The clashes came after the ministry refused to allow the Salafist group to hold its congress on security grounds.
Ansar al-Sharia is blamed for attacks on the US embassy as well as a private television channel and an art exhibition.
The screening of Persepolis, an animated film set in Iran during the Islamic Revolution, drew an angry reaction from supporters of the group who called the film blasphemous.
Prime Minister Ali Larayedh said Ansar al-Sharia would also be banned from holding congresses in future, according to TAP. The group had ties to terrorism and would be classified as an illegal organization, he said.
The moderate Islamist government has distanced itself from the group that rejects Western democracy and wants Islamic law applied in Tunisia.