Pakistan Citizenship Act, 1951 — section 4

4. Citizenship by birth. Every person born in Pakistan after the commencement of this Act shall be a citizen of Pakistan by birth: Provided that a person shall not be such a citizen by virtue of this section if at the time of his birth

(a)his father possesses such immunity from suit and legal process as is accorded to an envoy of an external sovereign power accredited in Pakistan and is not a citizen of Pakistan; or

(b)his father is an enemy alien and the birth occurs in a place then under occupation by the enemy.