Anti-US riots raging across the Islamic world are spreading to Asia and Africa, including non-Muslim countries such as India.

Outraged Muslims are targeting US missions. India's southern cities of Hyderabad and Chennai have witnessed protests against the US-produced film Innocence of Muslims.

Muslim activists hurled stones at the missions and ripped and burnt US flags. There have been no reported injuries to US staff.

A mob was prevented from scaling the walls of the US consulate in Chennai by police. Friday prayers were used to incite Muslims to protest against the US.

In Hyderabad, soon after evening prayers in a mosque, a group of Muslims spread the US flag like a carpet and walked on it.

The US State Department said that more than 65 of its embassies or consulates across the globe are on high alert as the volatile situation continues. Diplomatic activities of missions in Islamic countries have reportedly come to a standstill.

Apart from nearly 20 Islamic countries in the Middle East, US missions in Malaysia and Doha faced huge protests. Scores of Muslim children took part in the protests in the Bangladeshi capital Dhaka, while hundreds of marchers thronged the US diplomatic enclave in Nigeria.

One of the worst outbreaks of violence was reported in Tunis, where an American-run school was ransacked. Protesters scaled the walls, entered the premises and looted everything they could find. More than 650 students were sent home early.

"It's ransacked. We were thinking it was something the Tunisia government would keep under control. We had no idea they would allow things to go as wildly as they did," the director of the American Cooperative School of Tunis, Allan Bredy, told the New York Times.

More violence has occurred in Australia, where scores of activists clashed with the police outside the US consulate. The protesters carried placards reading: "Obama, Obama, we like Osama" and "Behead all those who insult the Prophet". Officials used tear gas to disperse angry crowds.