Tunisian public prosecutor Tarek Chkioua, under fire for pursuing cases against journalists, has been promoted to the country's Court of Appeal, a justice ministry list shows.

Currently prosecutor in the capital's court of first instance, he now becomes advocate general in the country's highest judicial body.

A Tunisian journalist was detained Friday for accusing the public prosecutor of fabricating evidence implicating a cameraman in an egg-throwing attack on a minister, a case stoking fears about curbs on free speech.

"The committal order was given even before our statements and the questioning of Zied el-Heni... This detention is illegal," the journalist's lawyer Moufida Belghrith told Agence France Presse, after he was summoned to the central courthouse in Tunis.

Tunisia's National Constituent Assembly on Wednesday partially resumed its activities, which had been suspended since early August due to a political crisis triggered by the assassination of an opposition MP.

The assembly's press service said three parliamentary commissions were called back for the first time since the speaker, Mustapha Ben Jaafar, ordered that their work be halted.

Tunisian prisons and detention centers are facing the risk of "terrorist" acts, the prison officers union said on Tuesday, with several attacks having reportedly been foiled already.

"The Tunisian authorities have been notified by the international organization Interpol about the existence of a terrorist threat against the prisons," the union's secretary general Olfa Ayar told a news conference.

Tunisian security forces on Monday killed two Islamist militants from the extremist group Ansar al-Sharia and arrested two others in a Tunis suburb, the interior ministry said.

The two men arrested, Mohammed Khiari and Mohamed Aouadi, are leaders of the Salafist movement's military wing and are implicated in the assassination of opposition lawmakers Chokri Belaid and Mohammed Brahmi, a ministry source said.

Thousands of Tunisians took to the streets of Bardo, near the capital Tunis, late Saturday, calling for the government led by the moderate Islamist Ennahda party to step down.

They were marking the end of a 40-day period of mourning after the assassination of opposition leader Mohamed Brahmi, shot dead outside his home on July 25.

Tunisia's minister of culture has withdrawn a lawsuit filed against a cameraman due to stand trial on Thursday for filming an artist hurling an egg at the official, his lawyer said.

"The minister (Mehdi Mabrouk) withdrew his complaint against Mourad Meherzi, who was only doing his job," the minister's lawyer Mabrouk Kourchid told Agence France Presse.

Around 50 common criminals escaped from jail overnight in southern Tunisia after attacking the guards, the head of the country's prison service Habib Sboui said on Monday.

Sixteen of the escapees were detained several hours after fleeing the prison in Gabes, he added.

Tunisia's Islamist-led coalition has failed to agree with the opposition on how to end weeks of political deadlock, mediators said on Saturday, ahead of planned anti-government protests.

Tunisia was plunged into crisis by the July 25 assassination of opposition MP Mohamed Brahmi, the second of its kind in six months, with both attacks blamed on militant Salafists.

Tunisia's ruling coalition on Friday presented mediators with a proposed compromise to end a crisis sparked by a political assassination last month, while refusing opposition demands that it resign immediately.

Mediators have been shuttling between the Islamist-led government and the opposition in a bid to end the political turmoil caused by the killing of opposition MP Mohammed Brahmi on July 25, an attack blamed on militant Salafists.