Article 3 of the Constitution of India

Formation of new States and alteration of areas, boundaries or names
of existing States.—Parliament may by law-

(a) from a new State by separation of territory from any State or by
uniting two or more States or parts of States or by uniting any
territory to a part of any State;

(b) increase the area of any State;

(c) diminish the area of any State;

(d) alter the boundaries of any States;

(e) alter the name of any State:

[ Provided that no Bill for the purpose shall be introduced in either
House of Parliament except on the recommendation of the President and
unless, where the proposal contained in the Bill affects the area,
boundaries or name of any of the States, the Bill has been referred by
the President to the Legislature of that State for expressing its
views thereon within such further period as the President may allow
and the period so specified or allowed has expired.]

Explanation I.- In this Article, in clauses (a) to (e), "State"
includes a Union territory, but in the proviso, "State does not
include a Union territory.

Explanation II.- The power conferred on Parliament by clause (a)
includes the power to form a new State or Union territory by uniting a
part of any State or Union territory to any State or Union territory.