A pin-drop silence engulfs Chandni Chowk square in the Pakistani garrison city of Rawalpindi around midnight.

Only the sounds of passing cars and howling stray dogs still punctuate the air as shopkeepers and vendors wrap up business following a long day.

A few dozen motorbikes roar past as young, bearded men ride to their overnight jobs.

The men are teachers at online seminaries established in recent years which teach Islam to people in the US and Europe through web-based platforms like Skype.

“This is a source of income for me as well as a holy duty of spreading Islam,” says Yasir Haroon, walking up a dark stairway of a multi-storey building to reach his office.

Haroon has been running a Skype seminary, also known as a madrasa, for three years from a small apartment.

Students from the US, Britain, France and the Netherlands study with him.

He has hired seven teachers, all graduates of Pakistani madrasas, to teach students how to read the Qur’an in Arabic and to explain its meaning along with basic Islamic principles.

“People in the West are interested in Islam,” Haroon explains, as the other teachers begin their daily lessons on Skype. “We have experienced an increase in demand.”

“This is how you should read this,” a teacher instructs his student, reciting a Qur’an verse after asking the young man on the other end to follow him.

Islamic centres in Western countries help madrasas enroll students, or simple online searches can also be used to make the connection, Haroon adds.

Students, mostly children from expat families from Pakistan, India and Bangladesh, take lessons individually or in small groups for up to half an hour a day.

Neither the government nor the federations which control conventional madrasas know exactly how many online seminaries there are in Pakistan.

“You can’t keep a tab on them,” says Amir Tuaseen, the head of the Pakistan Madrasa Education Board (PMEB). “All that you need is a computer and a Skype ID.”

“The number is very high...in the thousands,” guesses Imran Jamshed, who runs a seminary in the same city.

Online seminaries are operating not only in Pakistan but also in India and Bangladesh, Jamshed says.

Apart from markets like the US, Canada and Europe, the madrasas are also venturing into places like China and South Africa, says Maulana Rehmat Niaz, the owner of another seminary.

Niaz runs a seminary in the north-western town of Mansehra, and a number of Chinese Uighur Muslims have enrolled.

The Chinese government suspects that the East Turkistan Islamic Movement (ETIM), a group of Uighur Muslims from the north-western province of Xinjiang, is involved in terrorism and that its members have trained with Al Qaeda in the tribal regions of Pakistan.

However, there is no evidence of links between ETIM and students enrolled at Pakistan’s online madrasas.

Western citizens who convert to Islam also study the Qur’an and Islam at these madrasas, Jamshed adds, but those scenarios were rare.

A German mother and two of her teenage daughters recently enrolled with a seminary in Rawalpindi after they converted to Islam, Jamshed recalls.

“There aren’t enough mosques or Islamic centres in the US and Europe,” he says. “Muslims want their kids to learn the Qur’an and understand Islam and we provide what they need.”

There are around 20,000 conventional Islamic seminaries in Pakistan, teaching nearly two-and-a-half million students, according to PMEB.

Some of the madrasas have been linked to insurgent Taliban militants, according to the government.

Officials launched a push to streamline the seminaries under a programme called the National Action Plan, after Taliban militants killed nearly 150 school children in December 2014.

But these efforts met with failure, Tuaseen said.

“We haven’t been able to control regular madrassas so far,” Tuaseen says. “Forget about the ones that operate online.”