"The rules of natural justice were not confined to the narrow precincts of the prevailing definition of quasi-judicial functions." This principle was laid down in which case?

In the landmark judgment of A.K. Kraipak v. Union of India (AIR 1970 SC 150), the Supreme Court of India held that the rules of natural justice operate in the entire area of administrative functions and are not restricted only to quasi-judicial actions. The court observed that the dividing line between an administrative power and a quasi-judicial power is quite thin and is being gradually obliterated.