TUNIS: Tunisian police on Wednesday fired tear gas to disperse hundreds of Salafist demonstrators outside the US embassy in Tunis gathered to condemn a film deemed offensive to Islam, an AFP photographer said.

The intervention came as the demonstrators, estimated to number 300, started to try to break through the gates of the embassy compound after having demonstrated peacefully for several hours outside.

Five people were arrested, interior ministry spokesman Khaled Tarrouche told AFP, while a security official said on Tunisian radio that two policemen were injured, apparently by stone-throwing protesters.

Men and women protesters carrying black and white salafist flags had massed outside the diplomatic compound.

"Obama, we are all Osama!" some of the demonstrators chanted, referring to American President Barack Obama and Al-Qaeda chief Osama bin Laden who was killed by US commandos in May 2011.

Police deployed reinforcements at the already highly secure embassy blockhouse, with a military vehicle standing guard outside and motorbike units patrolling the area.

A source inside the compound told AFP the embassy was working as normal on Wednesday despite the violence in Libya and Egypt.

On Tuesday, US ambassador to Tripoli Chris Stevens and three other Americans were killed in the eastern Libyan city of Benghazi when an armed mob stormed the American consulate, torching the building after ransacking and looting it.

And in Cairo, several thousand people stormed the American embassy in a similar protest against the amateur American-made Internet video called "Innocence of Muslims."

The low-budget movie, in which actors have strong American accents, portrays Muslims as immoral and gratuitously violent. It also pokes fun at the Prophet Mohammed and touches on themes of paedophilia and homosexuality.

It was produced by Israeli-American Sam Bacile, according to the Wall Street Journal.