Earlier in April, a woman, Shari Baloch, had exploded herself outside the Karachi University, killing three Chinese teachers and their local driver.
The BLA had claimed responsibility for the suicide attack.
Addressing a presser today, Memon said that the suspect in police custody – Daad Baksh – has revealed that the attack was the joint plan of the BLF and the BLA.
He said that the suspect was arrested after collection of CCTV footage, geo-fencing and DNA sampling by the Counter Terrorism Department (CTD). "During the investigation process, the suspect made important revelations. He said that he was the commander of a BLF sleeper cell in Karachi."
The suspect also revealed that he had been conducting recce of different BLA targets on the orders of his organisation's commander, the minister said, adding that the suspect had conducted a recce of sensitive installations and of Chinese citizens working at KU.
Memon said that the suspect had met with the husband of the suicide bomber, Dr Haibastan Bashir, and another terrorist Zeb in Karachi, and helped to carry out the KU attack.
The suspect has revealed that Zeb was the mastermind of the KU attack, who entered Pakistan from a "neighbouring country" and had been staying in Karachi with Baloch and her husband, the minister added.
Memon said that terrorists trying to create unrest "would be eliminated" by the country's security agencies.