TUNIS: At least three people died and 28 others were wounded on Friday after police fought hundreds of protesters incensed by a U.S.-made film insulting the Prophet Mohammad who ransacked the U.S. embassy in Tunisia, state television said.

A Reuters reporter saw police open fire to try to quell the assault, in which protesters forced their way past riot police into the embassy.

The protesters smashed windows, hurled petrol bombs and stones at police from inside the embassy, or started fires in the embassy and the compound. A black plume of smoke rose from the facility.

One protester was seen throwing a computer out of a window, while others walked away with telephones and computers.

A Tunisian security officer near the compound said the embassy had not been staffed on Friday, and calls to the embassy went unanswered. A Reuters reporter saw two armed U.S. soldiers on the rooftop.

The protesters, many of whom were Islamic Salafists, also set fire to the nearby American School, which was closed at the time, and took away laptops and tablet computers.

The protests began after Friday prayers and followed a rallying call on Facebook by Islamist activists that was quickly endorsed by the local faction of the Islamic militant group Ansar al-Sharia.

Libyan officials suspect the Libyan branch of Ansar al-Sharia of being behind an attack in Benghazi in which four Americans, including the U.S. ambassador to Libya, were killed on Tuesday.

The moderate Islamist Ennahda movement, which heads the Tunis government, had advised Tunisians against participating in the protest.

"The (Tunisian) government does not accept these acts of aggression against foreign diplomatic missions," said a statement read on state television. It said Tunisian authorities were "committed to ensuring the safety of foreign diplomatic missions".

Hundreds of protesters wielding petrol bombs, stones and sticks had charged at the security forces protecting the embassy before jumping a wall to invade the compound.

"Obama, Obama, we are all Osamas," they chanted, in reference to the slain al Qaeda leader, Osama bin Laden.

The protesters pulled down the U.S. flag flying over the embassy, burned it, and replaced it with a black flag emblazoned with the Shahada, the Islamic declaration of faith.

Riot police finally drove the protesters from the embassy and the compound, and a Reuters reporter saw them arresting around 60.

The compound was cordoned off by police, soldiers and members of the elite presidential guard, but clashes continued in the el-Aouina district across a highway from the smart Auberge du Lac neighbourhood where the embassy is located.