Ghazal maestro Mehdi Hassan was on Sunday admitted to a hospital in this eastern Pakistani city after he complained of a chest infection and aching feet.
Doctors treating Hasan, 81, at the emergency ward said his blood pressure had shot up.
They had conducted preliminary medical tests and were hopeful of his early recovery, Geo News channel reported.
Hassan, born into a family of traditional musicians in Luna village in Rajasthan, has a large fan following in the subcontinent.
His family migrated to Pakistan at the time of partition. Hassan cut back on his performances in the late 1980s due to illness.