Fresh protests erupted Friday across the Islamic world, sparked by an Internet video produced in the United States that mocks the Prophet Muhammad.

Thousands of people took to the streets in Pakistan, where at least 17 people were killed and dozens wounded in clashes between security forces and protesters. The deadliest violence was in the southern city of Karachi, where at least 12 people were killed.

Demonstrations were also held in the capital, Islamabad, in Peshawar and Lahore, among other areas.

Pakistan's Foreign Ministry says it summoned U.S. diplomat Richard Hoagland to register a “strong protest” over the video. Hoagland reiterated U.S. condemnation of the film and emphasized the U.S. government had nothing to do with it.

The U.S. embassy in Pakistan ran advertisements on Pakistani TV that featured U.S. President Barack Obama and Secretary of State Hillary Clinton denouncing the video.

Pakistan's government designated Friday to be a national holiday and “a day of love for the Prophet Muhammad.”

Thousands of Muslims also protested in other countries, including Afghanistan, India, Sri Lanka, Bangladesh, Iraq, Lebanon and Indonesia. Some protesters burned American flags and effigies of Mr. Obama.

U.S. embassies across the Islamic world remain on high alert for protests.

In France, the government said it is closing its embassies, consulates, cultural centers and schools in 20 countries Friday as a precautionary measure. French authorities also banned two anti-U.S. protests planned for Saturday.

The French weekly Charlie Hebdo featured several images of the Prophet Muhammad in its Wednesday issue, including several of him naked.

Pakistani media said the government called on the army to protect Islamabad's diplomatic enclave.

Cell phone service was blocked in 15 Pakistani cities, including Islamabad and the eastern city of Lahore.

The low-budget Internet video was produced by an anti-Muslim filmmaker in California. It first sparked protests last week in Cairo and the Libyan city of Benghazi, where U.S. Ambassador J. Christopher Stevens and three other embassy personnel were killed. Since then, anti-U.S. protests have spread as far as Indonesia.

Pakistani Prime Minister Raja Pervez Ashraf told a conference of religious leaders and politicians in Islamabad that Pakistan is demanding the United Nations and other international organizations seek a law that bans “such hate speech, equal to the worst kind of anti-Semitism or other kinds of bigotry.”