Indian Post Office Act, 1898
10. Power to declare rates of foreign postage
(1) Where arrangements are in force with the United Kingdom, or with any British possession or foreign country, for the transmission by post of postal articles between 5[India] and the United Kingdom or such possession or country, the Central Government may, in conformity with the provisions of such arrangements, declare what postage rates and other sums shall be charged in respect of such postal articles, and may make rules as to the scale of weight, terms and conditions subject to which the rates so declared shall be charged.
(2) Unless and until such declaration as aforesaid is made, the existing rates and regulations shall continue in force.