By Asad Hashim
ISLAMABAD (Reuters) - Pakistan has rounded up more than 5,000 militant suspects, then released most of them, in the two days since a suicide bomber killed at least 72 people in a park in Lahore at Easter, a provincial minister said on Tuesday.
Investigators were keeping 216 suspects in custody pending further investigation, said Rana Sanaullah, a state minister for Punjab province from Prime Minister Nawaz Sharif's ruling party.
Details of the sweeping raids aimed at anyone suspected of violent Islamist extremism came as the Taliban faction claiming responsibility for the attack issued a new threat on Tuesday, singling out the media.
Sanaullah said "5,221 people have initially been detained. 5,005 have been released after verifying their identities, and 216 people have been referred for further investigation.
"If someone is found to be guilty, they will be charged," told journalists in the Punjab province capital of Lahore.
Army spokesman Gen. Asim Bajwa said the military and the paramilitary Rangers were conducting raids across Punjab, Pakistan's richest and most populous province, in rapid response to the Easter bombing.
"Right now in Rawalpindi, Multan and elsewhere, operations are ongoing, intelligence agencies and Rangers and army troops are carrying out operations," he told reporters in Islamabad.
Jamaat-ur-Ahrar, the Taliban faction that claimed responsibility for the blast aimed at Christians celebrating Easter, warned Pakistani media they could be the next target.
"Everyone will get their turn in this war, especially the slave Pakistani media," Ehsanullah Ehsan, spokesman for the group, tweeted. "We are just waiting for the appropriate time."
Even as authorities pursued Islamist militants across Punjab, hundreds of ultra-conservative Muslim protesters remained camped out in front of parliament on Tuesday in the capital, Islamabad, days after clashing with police.
Mobile phone networks in the capital were blocked for security purposes for a second day in a row.
The Easter bombing was Pakistan's deadliest attack since a 2014 school massacre claimed by the Taliban killed 134 students.
The attack, which included 29 children among the 72 dead, showed the militants can still cause carnage despite military raids on their northwestern strongholds.
Lahore is the capital of Punjab, Pakistan's richest and most populous province and Sharif's political heartland.
"Let Nawaz Sharif know that this war has now come to the threshold of his home," tweeted Ehsan. "The winners of this war will, God willing, be the righteous mujahideen."
Sanaullah said at least 160 raids have been carried out since Sunday night by a mixture of police, counter-terrorism and intelligence agents and confirmed that army and paramilitary forces would be used in future operations.
"This operation will include all law enforcement agencies," Sanaullah said.
Military and government officials on Monday said that the army was preparing to launch a new paramilitary counter terrorism crackdown in Punjab, as it did more than two years ago in the violent southern megacity of Karachi.
By allowing this, the civilian government once again ceded special powers to the military to fight Islamist militants.
Punjab provincial leaders, particularly among Prime Minister Sharif's party, have long resisted suggestions of bringing in the paramilitary Rangers to fight extremism in reported centers of radicalism including Multan in southern Punjab.
In Karachi, the Rangers' crackdown has cut back the rate of militant and criminal violence sharply, but also drawn accusations of human rights abuses and the targeting of opposition politicians.
A possible renewal of their mandate by the Sindh provincial government is the subject of heated debate there.
Army spokesman Gen. Bajwa said the government had agreed to send whatever forces are most appropriate to capture extremists.
Jamaat-ur-Ahrar, which has declared loyalty to Islamic State, has carried out five major attacks in Pakistan since December.
In recent years, Pakistan has cracked down on movements that target its own citizens and institutions, including the Pakistani Taliban who are fighting to topple the government and install a strict interpretation of Islamic law.
The army and former governments have been accused of fostering hard-line religious movements to boost their own support and to use militant groups to help pursue objectives in Afghanistan and against Pakistan's old rival India.
However, moves by the government to crack down on extremism have prompted a backlash.
The recent outpouring of anger over the execution in late February of ex-bodyguard Mumtaz Qadri, who assassinated the Punjab governor he guarded because the politician campaigned against Pakistan's harsh blasphemy laws, highlights the tension.
The demonstrators, incensed by the hanging of a man they consider a hero for defending Islam, now demand the immediate execution of hundreds of people in jail on blasphemy charges.
(Writing by Kay Johnson; Editing by Tom Heneghan)