Pakistan on Thursday blocked access to an anti-Islam film as security measures beefed up around US diplomatic missions, following attacks on American consulates and embassies in Libya, Egypt and Yemen.
The Afghan government earlier ordered an indefinite ban on the entire YouTube video sharing site to prevent access to the film made in the United States, which Kabul said was offensive to Muslims.
"Pakistan Telecommunication Authority (PTA) has proactively blocked and vigorously preventing all access to anti-Islamic video placed on worldwide web via YouTube with the name of Innocence of Muslims," it said in a statement.
It said "the authority is in close liaison with all the service providers for immediate blocking of the provocative video", adding that "proactive monitoring and blocking is being done, round the clock".
The PTA, which is the main regulatory authority, is mandated to block blasphemous and pornographic websites.
"Websites which contain offensive, objectionable and obnoxious material are blocked on the direction of the government as per mandated protocols," said the statement.
A spokesman for the Internet Service Providers Association of Pakistan, Wahaj us Siraj, told AFP that the ISPs have blocked all the URLs with the film.
"We have fully implemented orders of the PTA and will make sure that the film is not accessible to anyone in Pakistan," Siraj added.
Pakistan's government said the "abominable" production was designed to stoke inter-faith hatred around the anniversary of the September 11, 2001 attacks, while Afghan authorities condemned the film as "inhuman and insulting".
"We have beefed up the security for the possible threats to the US embassy," Khurram Rasheed, a senior Pakistani police official responsible for diplomats' security in Islamabad, told AFP earlier Thursday.
"We expect some protests against the embassy tomorrow and we are preparing to handle that," he said.
Riots this week erupted over the film in Libya, where a mob stormed the US consulate in the eastern city of Benghazi on Tuesday, killing US ambassador Christopher Stevens and several other staff members.
There were also anti-US protests in Egypt's capital Cairo and on Thursday a crowd stormed the American embassy complex in the Yemeni capital Sanaa before being driven out by police.
The low-budget movie, entitled Innocence of Muslims, portrays followers of the faith as immoral and gratuitously violent.
The film has been promoted by controversial US pastor Terry Jones, who has drawn protests for previously burning the Koran and vehemently opposing the construction of a mosque near Ground Zero in New York.