Pakistani authorities are suspending mobile phone services in major cities to prevent sectarian violence during key Shia Muharram commemorations.
More than 90% of bombs are detonated by attackers using phones, officials say.
In some areas, motorbikes carrying passengers have been banned because of fears that this is how attackers could be brought to their targets.
Attacks on minority Shia by hard-line Sunnis have increased in recent months across Pakistan.
In the deadliest attack this week, 23 people were killed at a Shia procession in the city of Rawalpindi.
On Friday, mobile phone services were temporarily blocked in parts of the capital Islamabad, the southern port city of Karachi, and in Quetta in the south-east.
Pakistani authorities are suspending mobile phone services in major cities to prevent sectarian violence during key Shia Muharram commemorations
The authorities said that more areas would be cut off over the weekend – the climax of the holy month of Muharram for Shias.
“More than 90% of bomb blasts have been carried out through mobile sims,” Pakistani Interior Minister Rehman Malik told reporters.
“Most recently, all the blasts that occurred in the last 15 days were mobile phone-based,” he added.
Thousands of extra police are also being deployed and aerial surveillance will be carried out to monitor Shia processions across the country.
Muharram marks the anniversary of the battle where the grandson of the Prophet Mohammad was killed.
Nakoula Basseley Nakoula, the man linked to anti-Islam video Innocence of Muslims that sparked riots across the Muslim world, has been held without bond after a hearing in Los Angeles, California.
A judge said Nakoula Basseley Nakoula was a flight risk and cited a pattern of deception when making his ruling, Reuters news agency reported.
Nakoula Basseley Nakoula was investigated for violating probation terms after he was released from prison in 2011 for bank fraud.
He has not been detained over the contents of the inflammatory video.
Nakoula Basseley Nakoula, a 55-year-old Christian originally from Egypt, allegedly produced the 14-minute trailer for the film Innocence of Muslims. He had been in hiding after the release of the video.
Nakoula Basseley Nakoula has been held without bond after a hearing in LA
After his 2010 conviction, he was sentenced to 21 months in prison and, under the terms of his probation, he was banned from using computers or accessing the internet for five years without an officer’s permission.
US Central District Chief Magistrate Judge Suzanne Segal said: “the court has a lack of trust in this defendant at this time”.
Assistant Attorney Robert Dugdale said the court believed Nakoula Basseley Nakoula was flight risk.
“He has every incentive to disappear,” he said.
A clip from the US-made film was dubbed into Arabic, provoking widespread anger for its disrespectful portrayal of the Prophet Muhammad.
The film was made on a very low budget, with insults and offensive inferences to the Prophet Mohammad and Islam crudely dubbed on afterwards.
Earlier, the Obama administration had requested Google, the company that owns YouTube, to remove the clip. The technology firm refused, saying the film did not violate its rules.
The clip was uploaded to YouTube in July, but violence only broke out on 11 September, after Arabic TV stations broadcast it.
The clip has not broken any laws in the US, where freedom of speech is enshrined in the constitution’s first amendment.
Four Americans, including US Ambassador Christopher Stevens, were killed in an attack on the US consulate in Benghazi, Libya earlier this month.
Meanwhile, some of the actors in the video have come forward to say they were misled. They said had been hired to appear in a film called Desert Warriors, which did not mention Islam or the Prophet Muhammad in the script.