Three Pakistani bloggers have been accused of blasphemy in an Islamabad counterterrorism court, an offense punishable by death.
Police and government officials on March 24 said the charges were set against two bloggers from Pakistan's southern city of Karachi and one from Islamabad.
Officials said they were arrested earlier this week. They are being held for seven days while their online activity is probed, an official said.
One of the bloggers, using the alias Allama Ayaz Nizami, had 12,000 followers, said the official, who did not want to be identified.
Authorities said laptops of the detainees had also been seized for forensic analysis.
The arrests come after Prime Minister Nawaz Sharif on March 14 ordered that "blasphemous" content on social-media websites be removed or blocked.
He said those responsible for posting such material will be "strictly punished."
Blasphemy is a criminal offense in Pakistan and can carry the death penalty.
It is a highly sensitive issue in a country where dozens have been murdered over blasphemy allegations, according to the Center for Research and Security Studies.
At least five other bloggers were earlier charged with insulting Islam. They have since fled the country after receiving death threats, the Associated Press reported.
Those bloggers said the charges were in retaliation for their criticism of the military and intelligence agencies.