The meeting was earlier scheduled at the Chief Minister House, however it was cancelled and shifted to the Governor House.
According to sources, the PM is likely to take key decisions during the meeting on Karachi situation.
Meanwhile, the PM has announced observance of countrywide day of mourning on Thursday over Karachi bus tragedy. The national flag would fly at half mast.
The Prime Minister said the entire nation shares grief and sorrow of the bereaved families.