Renowned rights activist and university professor Salman Haider disappeared from the capital Islamabad on Friday, according to his relatives and human rights organizations. Authorities have ordered an investigation into his possible kidnapping, but have not yet located him.

Three other secular activists - Waqas Goraya, Asim Saeed and Ahmed Raza - are also missing. While all these people work in different fields, they all have one thing in common: their consistent and sharp criticism of Pakistan's security establishment and conservative groups.

The "missing persons" phenomenon is not new in Pakistan. Thousands of people have disappeared over the past few years, but most of them are connected with an ongoing separatist movement in the western Balochistan province or the Islamist insurgency in the northwestern tribal areas bordering Afghanistan. In both places, the army is operating against "miscreants" and "terrorists," which it believes are working against the state.

Local rights groups have the details of at least 8,000 people they say have disappeared over the past 12 years without a trace.

Baloch men and women have taken to the streets in a protest over apparent kidnappings

But the disappearance of secular writers and activists is a relatively new "trend" in the majority Muslim South Asian nation. Rights groups have been alarmed by it, saying it is a big threat to the free speech in the country.

"Forced disappearances are not a new phenomenon in Pakistan. In the past, it was mostly restricted to the kidnappings of people from Balochistan and the southern Sindh province, but now we see a nationwide situation," Farzana Bari, a prominent social activist in Islamabad, told DW.

Leftist activist Farooq Tariq says the civil society groups will hold demonstrations in many Pakistani cities against the disappearances of Haider, Goraya, Saeed and Raza on Tuesday.

Liberalism versus orthodoxy

"The civil society needs more unity now to protect the freedom of speech in the country. In the age of social media, independent thinkers have a platform to voice their concerns against certain actions of the government, and it is their right," Nahyan Mirza, an Islamabad-based development professional, told DW.

"Pakistani society, unfortunately, is being controlled to a large extent by the right-wing. These groups will never tolerate social, cultural and intellectual change that poses a challenge to its power. But I am hopeful the change will come soon," Mirza added.

The activists' disappearance is not only condemned in Pakistan but across the world, especially among the Pakistani diaspora.

Asim Ali Shah, a leftist member of the London-based Faiz Cultural Foundation, doesn't directly accuse the government for the kidnappings, but rather views the issue as a failure by the state to protect the country's intellectuals.

"The government's National Action Plan to eradicate terrorism has been a total failure. We see the extremist literature that promotes hatred, sectarianism and intolerance is in circulation all across the country. Yet the state only cracks down on progressive bloggers, peaceful writers and political activists," Shah told DW, adding that the democratic and progressive overseas Pakistanis will organize a series of protests to demand the immediate release of all missing persons.

They will be raising the issue on international forums and also with British parliamentarians, he says.

Religious groups enjoy more public support than liberals in Pakistan

The flipside

But there are also people in Pakistan who say the liberal sections only protest when one of their "comrades" disappears, and that they never raise their voices against the military operations in the tribal areas that, according to them, have killed thousands of innocent people. They argue that many people with no links to the Taliban or any other militant group have disappeared in those areas, yet the civil society is silent about them.

"The missing persons belonging to the Islamist camp have never been an issue for the Pakistani liberals. They were happy when former military dictator Pervez Musharraf acted unlawfully against Islamic clerics and activists," Naufil Shahrukh, an analyst at the Islamabad-based Institute of Policy Studies (IPS), told DW.

"The US drone killings in the northwestern tribal region, and the kidnappings and extra-judicial killings of anti-Musharraf people never bothered the secular groups. The case of Pakistani neuroscientist Aafia Siddiqui, who is imprisoned in the US, is just one example of this hypocrisy," Shahrukh underlined.

Outcry on the social media

Nonetheless, #RecoverSalmanHaider has been trending on Pakistani social media since the disappearance of the university professor.

While some people are accusing the security agencies for the alleged kidnapping, the others say Haider was "abducted" because he belongs to the minority Shiite sect of Islam.

Sectarian conflict has spiked in the South Asian country in the past few years. Hundreds of Shiite people have been killed by the Sunni Deobandi groups that support Saudi Arabia against Iran.

It remains unclear who was behind Haider's disappearance, but what is quite clear is that the progressive writers and intellectuals are increasingly worried for their safety. But many secular-minded people in Pakistan say they are not ready to give up the fight.

Additional reporting by Sattar Khan, DW's Islamabad correspondent.