The U.S. State Department has ordered the departure of all family members and non-essential U.S. government personnel from posts in Sudan and Tunisia and is issuing travel warnings to American citizens in the two countries due to security concerns over anti-American violence.

"Given the security situation in Tunis and Khartoum, the State Department has ordered the departure of all family members and non-emergency personnel from both posts, and issued parallel travel warnings to American citizens," Victoria Nuland, a department spokeswoman, said Saturday.

The department's travel warning said while Sudan's government has taken steps to limit the activities of terrorist groups, some remain there and have threatened to attack Western interests. The terrorist threat level remains critical.   

The State Department said the airport in Tunis was open and it encouraged all U.S. citizens to depart by commercial air. It said Americans in Tunisia should use extreme caution and avoid demonstrations.

Rick Roth, a spokesman for Foreign Affairs Minister John Baird, said the embassies in Cairo, Tripoli and Khartoum were to close for the day on Sunday as a security precaution. The Canadian mission in Tunisia is normally closed on Sunday.

The warnings were issued as anti-American protests continued to percolate around the world, from Egypt to Australia, over a 14-minute film by a California man lampooning the Prophet Muhammad and denigrating Islam.

Al-Qaeda group urges attacks

Al-Qaeda's branch in Yemen praised the killing of the U.S. ambassador in Libya in an internet statement Saturday and called for more attacks to expel American embassies from Muslim nations.

Ambassador Chris Stevens and three other Americans were killed after an attack on the U.S. consulate in the Libyan city of Benghazi on Tuesday. 

Al-Qaeda in the Arabian Peninsula called for protests to continue in Muslim nations "to set the fires blazing at these embassies," and said the killing of Stevens was "the best example" to follow.

In Cairo, police blocked roads leading to the U.S. Embassy after four days of demonstrations in Egypt.

After another night of skirmishes with protesters, riot police rounded up hundreds of people early Saturday in the streets near the embassy and Tahrir Square.

CBC's Sasa Petricic, reporting from the edge of the square, said traffic was flowing and people were cleaning up after a violent night. He said police were moving huge concrete blocks into place to block the main street leading to the embassy.

"You can still smell the tear gas. There are burned-out cars, lots and lots of broken windows along pretty much all of the streets here, at banks, hotels and other buildings. It's really quite a mess."

Muslims angry over the film mocking the Prophet Muhammad took to the streets on Friday in more than 20 countries from the Mideast to Southeast Asia.

In most countries, protests were peaceful, if vehement. But deadly clashes erupted in several places. Protesters in Sudan and Tunisia tried to storm Western embassies, an American fast-food restaurant was set ablaze in Lebanon, and international peacekeepers were attacked in the Sinai.

The deployment of an elite team of U.S. Marines to Khartoum has also been delayed, and possibly curtailed, due to objections by Sudan's government. The Marine unit, known as a fleet anti-terrorism security team, was ordered to Sudan in the wake of violence and protests against the U.S. Embassy there.

The anti-U.S. protests that have spread to so many Muslim-dominated countries began in Cairo on Tuesday. One man died of birdshot in Cairo overnight near the U.S. Embassy.

Anger over the controversial film, entitled The Innocence of Muslims, is blamed for an assault late Tuesday on the U.S. consulate in Benghazi, Libya, where assailants launched a two-pronged attack that killed four Americans, including Ambassador Chris Stevens.

The only report Saturday of violence linked to the film came from Sydney, Australia, where riot police clashed with about 200 protesters at the U.S. consulate.

Ten Network television news showed a policeman knocked unconscious as the mostly male crowd hurled bottles and other projectiles. Police used pepper spray against the protesters, who chanted "Obama, Obama, we love Osama" and waved placards saying "Behead all those who insult the Prophet."

Six police were injured and two protesters were treated for police dog bites police said in a statement.

With files from The Associated Press