Libya's assembly head, Mohammed al-Megaryef, said on Saturday that foreign elements could be involved in the deadly attack on the U.S. consulate in the coastal city of Benghazi.

"There are non-Libyan elements on Libyan soil and they plan to carry out their own agendas on our territory," the General National Congress president told Agence France Presse in an interview.

U.S. President Barack Obama urged Americans Saturday not to be disheartened by images of anti-American violence in the Islamic world, expressing confidence that the ideals of freedom America stands for will ultimately prevail.

"I know the images on our televisions are disturbing," Obama said in his weekly radio and Internet address. "But let us never forget that for every angry mob, there are millions who yearn for the freedom, and dignity, and hope that our flag represents."

President Barack Obama has vowed to "stand fast" against spreading anti-U.S. violence raging in the Arab world, as he mourned four Americans slain in Libya after their remains were flown home.

In a heart-rending homecoming, four transfer caskets draped in American flags were slowly borne Friday from the belly of a giant C-17 transport plane by Marines in dress uniform, and set down in a hangar.

Yemeni security forces fired warning shots and water cannon to disperse hundreds of protesters trying to reach the U.S. embassy in Sanaa on Friday, an Agence France Presse correspondent reported.

The protesters, angered by an anti-Islam film produced in the United States, gathered about 500 meters away from the embassy compound, calling for the expulsion of the U.S. ambassador as they burnt the American flag.

Russian President Vladimir Putin said Thursday the Middle East was at risk of descending into "chaos" following a deadly attack on the U.S. mission in Libya and incidents in Egypt and Yemen.

"We are afraid that the region may descend into chaos, which is essentially what is happening already," he said in comments broadcast on state television from his summer residence in the Black Sea resort of Sochi.

The U.S. Department of the Treasury imposed on Thursday sanctions against Hizbullah's leadership in Lebanon, further exposing Hizbullah's active support to the regime of Syrian President Bashar Assad, as well as its role in terrorist activities.

“Hassan Nasrallah, Hizbullah's secretary general, is being designated today pursuant to Executive Order (E.O.) 13582, for providing support to the Syrian government,” said the Treasury in a statement.

Grand Mufti Sheikh Mohammed Rashid Qabbani urged on Thursday the Lebanese people to unite in denouncing the film mocking Islam, calling on Christians and Muslims across the world to reject attempts to create incitement among them.

“If they succeed in their attempts we will only sow useless bloody conflicts,” Qabbani said in a statement.

Al-Qaida on Thursday posted an online video of two plane hijackers of the September 11, 2001 suicide attacks, which they said were part of a war to drive U.S. forces out of the Arabian Peninsula.

Salim al-Hazmi and Khalid al-Mihdar, two of the 19 extremists who hijacked the four airliners, appeared reading their wills, in a video produced by As-Sahab media arm of al-Qaida and provided by the U.S.-based SITE Monitoring Services.

Police used tear gas as they clashed on Thursday with a stone- and bottle-throwing crowd protesting outside the U.S. embassy in Cairo at a film mocking Islam, witnesses and the interior ministry said.

The health ministry said 13 people were injured during sporadic clashes through the night outside the embassy, where on Tuesday thousands of protesters tore down the Stars and Stripes and replaced it with a black Islamic flag.

A man was charged with terrorism offences in Australia Thursday after a series of raids connected to a Melbourne Islamic center.