The latest development follows the arrest of two facilitators involved in the attack earlier this week.
According to police sources, the facilitators were apprehended from Dera Ismail Khan and Lahore. The terror group had entered Lahore from South Punjab. The arrested suspects were moved to an undisclosed location for interrogation, the sources added.
On Thursday, a picture showing one of the alleged facilitators of the suicide bombing was released. A reward of Rs 1 million has been announced for information pertaining to the facilitator.
At least 14 people were martyred including two senior police officials in a suicide attack in Lahore on February 13. The suicide bomber hit close to the Punjab Assembly when hundreds of demonstrators had gathered for a protest.