NEW DELHI: The Supreme Court on Tuesday asked the Centre to file within four weeks its response on a petition challenging the validity of the National Investigation Agency Act, 2008.

Additional Solicitor General Aishwarya Bhati, appearing for the Centre, told a bench of Justices Vikram Nath and Sandeep Mehta that the government needed some time to file the counter affidavit.

Senior advocate Siddharth Dave, appearing for the petitioner, said that notice was issued on the plea on April 21.

The bench granted four weeks to the Centre to file the counter affidavit, and said the petitioner may a file rejoinder, if any, within two weeks thereafter.

It said the plea would be listed for hearing after six weeks.

On April 21, the top court sought responses from the Centre, the National Investigation Agency (NIA) and others seeking their responses on the plea.

The apex court had observed that questions raised before it were of vital importance.

The plea has sought the setting aside of the 2008 Act, claiming it was "violative" of Article 14 (equality before law) of the Constitution and beyond the legislative competence of the Centre.

The NIA was set up under the Act as a central counter-terrorism law enforcement agency in the wake of the 26/11 Mumbai attacks.

The plea said that 'police' falls under the State List.

It also referred to Section 6 (5) of the Act, which deals with the investigation of scheduled offences and says if the Centre is of the opinion that a scheduled offence has been committed which is required to be investigated under this Act, it may suo motu direct the agency to probe it.