U.S. President Barack Obama on Thursday called his Tunisian counterpart Beji Caid Essebsi to offer condolences for the deadly museum attack and continued assistance in the investigation.

Obama "extended sympathy, on behalf of all Americans, to the victims' families and loved ones," the White House said, following the attack on the Bardo Museum in Tunis which killed 21 people.

Tunisia's first presidential election since the 2011 revolution is a ray of hope for Arab Spring countries, Prime Minister Mehdi Jomaa said Saturday, on the eve of the historic poll.

Sunday's first multi-candidate presidential election is seen as the final stage of a post-revolt transition in the birthplace of the Arab Spring, with more than 20 candidates vying for the post.

A Tunisian court sentenced two policemen to 15 years Thursday for the rape of a woman who was herself almost put on trial, in an appeal that doubled their initial penalty.

Monia Bousselmi, a lawyer for the victim, hailed the ruling as "a great step" forward for such cases in the Muslim country.

An exiled son-in-law of deposed Tunisian president Zine El Abidine Ben Ali returned to the capital Tuesday to challenge a jail sentence for having a gun, his lawyer told Agence France Presse.

Businessman Slim Chiboub, who has been living in the United Arab Emirates since Ben Ali fled Tunisia in January 2011 during a popular uprising, had been sentenced in absentia to five years in jail for illegal possession of a firearm.

A raid by Tunisian security forces on an armed group near the capital Friday left six suspected militants dead, including five women, fanning tensions days ahead of a landmark election.

Tens of thousands of soldiers and police will be deployed for Sunday's parliamentary polls -- the first since an uprising three years ago that inspired the Arab Spring revolutions.

Amnesty International welcomed Wednesday the release of a Tunisian jailed for posting caricatures of the Prophet Mohammed but called for his sentence to be quashed and his name cleared.

Jabeur Mejri, 29, was freed Tuesday, two years into a seven-and-a-half-year sentence. His release came two weeks after a presidential pardon.

A Libyan air force medical plane crashed south of Tunis early on Friday, killing all 11 people on board, Tunisian officials said.

The aircraft crashed in a field on the edge of the village of Nianou, around 40 kilometers (25 miles) from the capital, but managed to avoid any houses, an AFP journalist reported.

A firefight between security forces and suspected Islamists holed up in a building in the Tunisian capital left a policeman and seven militants dead, the interior ministry said on Tuesday.

"Seven terrorists died. A member of the National Guard was killed and another wounded," a ministry source told Agence France Presse.

Unemployed Tunisian youths ransacked an empty police post in the impoverished central region of Gafsa overnight and torched its contents, witnesses told Agence France Presse on Monday.

Tunisia remains prey to sometimes violent social unrest, especially in the neglected center of the country, three years after an impoverished street vendor set himself on fire in a desperate act of protest that sparked the first Arab Spring uprising.

"A gang" of around 60 people attacked the headquarters of a coalition of political parties opposed to Tunisia's ruling Islamists in Tunis overnight on Thursday-Friday, the opposition group announced.

"A paid gang tried to attack the headquarters of the Popular Front. There was no damage and our colleagues are fine... The cowards fled" when confronted by members of the leftist coalition, the group said on its official Facebook page.