Hardline Islamists called for the deaths of senior judges and the overthrow of Imran Khan after a Christian woman sentenced to death for blasphemy was acquitted.
Asia Bibi had spent nearly eight years on death row in a case attracting international outcry, before she was freed on Wednesday by Pakistan’s top court.
The release of the mother-of-five immediately sparked nationwide protests from religious extremists who had campaigned for her to hang.
Imran Khan, the new prime minister, appealed for calm as crowds blocked highways and main roads and clashed with police.
The Catholic farmhand who was falsely accused of defaming the Prophet Mohammed now faces a life in hiding, or asylum abroad.
Diplomats are understood to have spent weeks planning how to spirit her out of the country in the event of her acquittal, with Mike Pence, US vice president, taking a personal interest in her fate.
The overturn of her 2010 conviction also led to fresh calls to reform Pakistan’s harsh blasphemy laws, which critics say are used to persecute religious minorities and justify censorship, or even murder.
"I can’t believe what I am hearing, will I go out now? Will they let me out, really?" Bibi told AFP by phone from prison after the ruling.
"I just don’t know what to say, I am very happy, I can’t believe it.”
Her daughter, Eisham Ashiq, described the acquittal as “the most wonderful moment in my life”.
“ I want to hug my mother and then celebrate with my family. I am grateful to God for listening to our prayers.”
Mrs Bibi’s ordeal began in 2009 as she picked berries in a Punjab field with others and was asked to fetch water.
Muslim women working alongside her allegedly objected, saying that as a non-Muslim she was unfit to touch the water bowl. Heated words were exchanged and the women then complained to a local cleric and accused her of blasphemy, a charge punishable by death. Mrs Bibi denied blasphemy but was rounded up by a village mob and was eventually sentenced to hang.
The three-member appeal panel of supreme court justices criticised the case against her, which Mrs Bibi had always said was fabricated to settle a score. The prosecution case relied only on her accusers’ testimony and a confession extracted by the mob.
"The appeal is allowed. She has been acquitted. The judgement of high court as well as trial court is reversed. Her conviction is set aside," said Pakistan’s Chief Justice Saqib Nisar in the ruling.
But the ruling provoked immediate anger from hardliners, over a case which has proven deeply divisive in Pakistan. Two senior government figures have already been killed after trying to help Mrs Bibi. Salmaan Taseer, the Punjab governor, was assassinated by his own bodyguard after calling for Mrs Bibi’s release and reform of blasphemy laws. The killer, Mumtaz Qadri, was executed in 2016 and has been feted as a hero by hardliners.
A leader of the Islamist political party Tehreek-e-Labaik (TLP), which was founded to support blasphemy laws, issued an edict that “all those who ordered the release of Asia deserve death”.
Omar Waraich, Amnesty International’s deputy South Asia director said Mrs Bibi had been left to languish in prison on flimsy evidence.
He said: “This was a case that was used to rouse angry and violent mobs, to justify the assassinations of two senior officials in 2011, and to intimidate the Pakistani state into submission. Mercifully, justice has prevailed. A clear message must now go out that the blasphemy laws will no longer be used to persecute Pakistan’s long-suffering religious minorities.”