Raja Umar Khattab, chief of the Counter Terrorism Department, said the hunt was launched after police arrested the suspected financier of a gun attack on a bus that left 44 people dead in May.
The attack on the bus, which was carrying members of the city’s Ismaili minority, was the first inside Pakistan officially claimed by IS, which has proclaimed a “caliphate” over territory it has seized in Iraq and Syria and is seeking to expand its global reach.
Khattab said the suspect, whom he named as Adil Masood Butt and who was arrested last week, confessed to police that his wife had established a religious organisation in the city called ‘Al Zikra Academy’.
“The academy has no organisational structure or offices,” Khattab told AFP.
“A group of 20 women, all from well-off families, distributed USBs (computer memory sticks) containing Islamic State videos, and also preached in support of terror organisations. They also arranged marriages among the group’s followers,” he added.
He said the group collected funds for terrorists in the name of Islamic charity which were later handed over to the suspect.
“The wife and mother-in-law of the main suspect of the carnage, Saad Aziz, were also part of the network,” he added.
Aziz, a graduate of one of the country’s top business schools, was blamed by police for both the massacre and the shooting of peace activist Sabeen Mahmud in April. He was arrested in May.
Khattab said efforts were being made to track and arrest the women.
For over a decade Pakistan has been waging a war against Islamist fighters that has claimed the lives of tens of thousands of civilians.
The fighting has been led mainly by Al-Qaeda, the Pakistani Taliban and its affiliates, though there are signs that the appeal of IS is growing among the affluent and educated classes who are motivated more by the idea of global jihad than local causes.
Islamabad denies IS is a major threat, though the police chief of Sindh province, of which Karachi is the capital, told a parliamentary standing committee in October that IS was behind the bus attack and that 14 people had been arrested for alleged links to the group.