New protests erupted across the Muslim world Friday, where anger is spreading over an anti-Islamic video posted on the Internet.

The most recent protests broke out in Tunisia's capital of Tunis, where police fired tear gas at rock-throwing demonstrators, some of whom were amble to jump over the wall surrounding the U.S. embassy.

The violence also spread to Sudan, where witnesses said police clashed with thousands of protesters heading toward the U.S. embassy. Protesters are also reported to have breached the German embassy.

Friday was the fourth day of protests about the film, which was a topic of conversation at Friday prayers across the Middle East, south and east Asia and Africa. Many demonstrators have been targeting countries they feel have not done enough to stop the video from being made.

U.S. and other foreign missions stepped up security following violent attacks that began Tuesday.

Some of the biggest demonstrations have taken place in Cairo, where protesters near the U.S. embassy Friday were met by police, who responded by firing with tear gas.

Protests have also taken place in Malaysia and Indonesia and security was tight in Kabul, Afghanistan.

In Benghazi, Libya, where the U.S. ambassador and three other American personnel were killed in an attack Tuesday, security was stepped up around the city and the airport temporarily closed.

U.S. warships are headed to the Libyan coast, while additional U.S. marine guards were deployed to protect the American embassy in Yemen, breached by protesters Thursday.

In many Cairo mosques Friday, the video, a crudely-made attempt to mock the Prophet Muhammad, was the topic of the day. One imam reminded worshippers that Egyptians, under their new, Islamist government, can now openly defend the prophet from such insults.

Egyptian President Mohamed Morsi, who has condemned the video, spoke out again Friday on the need to keep protests in check.

Egyptian security forces built a barrier Friday to block the route to the embassy. Egyptian police used tear gas earlier to break up the protests.

U.S. President Barack Obama spoke Thursday about the relationship between the United States and Egypt.

“I don't think that we would consider them an ally, but we don't consider them an enemy. They are a new government that's trying to find its way. They were democratically elected. I think we have to see how they respond to this incident.”

Libyan officials said Thursday that they have arrested four people in connection with this week's assault on the U.S. consulate in Benghazi that killed U.S. Ambassador Christopher Stevens and three of his staff. The officials did not provide details.

American intelligence agencies are examining the alleged involvement of pro-al-Qaida militants. But they say they do not have solid evidence.

U.S. Secretary of State Hillary Clinton condemned the amateur U.S.-made movie that mocks the Islamic Prophet Muhammad. She called it “disgusting” and “reprehensible.”