It was on section 69A and the Blocking Rules that the Government drew, for example, in the wake of the exodus from Bangalore of large numbers of Indians from the North East, in August 2012.
The law reads:
69A. Power to issue directions for blocking for public access of any information through any computer resource
(1) Where the Central Government or any of its officer specially authorised by it in this behalf is satisfied that it is necessary or expedient so to do, in the interest of sovereignty and integrity of India, defence of India, security of the State, friendly relations with foreign States or public order or for preventing incitement to the commission of any cognizable offence relating to above, it may subject to the provisions of sub-section (2), for reasons to be recorded in writing, by order, direct any agency of the Government or intermediary to block for access by the public or cause to be blocked for access by the public any information generated, transmitted, received, stored or hosted in any computer resource.
(2) The procedure and safeguards subject to which such blocking for access by the public may be carried out; shall be such as may be prescribed.
(3) The intermediary who fails to comply with the direction issued under sub-section (1) shall be punished with an imprisonment for a term which may extend to seven year and also be liable to fine.
The full text of the Blocking Rules can be found at the very bottom of this page.