4. Every person born in Bangladesh after the commencement of this Act shall be a citizen of Bangladesh 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 Bangladesh and is not a citizen of Bangladesh ; or(b) his father is an enemy alien and the birth occurs in a place then under occupation by the enemy.