The Supreme Court on Wednesdaygave the Centre four weeks to respond to pleas challenging the validity of the Citizenship Amendment Act (CAA) and said it will set up a five-judge Constitution bench to hear the petitions.While making it clear that it will not grant any stay on the CAA without hearing the Centre, a bench headed by Chief Justice S A Bobde restrained all high courts from hearing pleas on CAA till it decides the petitions.The bench said it will hear petitions pertaining to Assam and Tripura separately as the problem with CAA in these two states is different from rest of the country."The petitions concerning Assam and Tripura as well as matters related to Uttar Pradesh, which is going ahead with the implementation of CAA without framing any rules, can be dealt with separately," the court said.Attorney General K K Venugopal, appearing for the Centre, told the bench that the government has been given copies of around 60 pleas out of the 143 petitions.He said it wanted time to respond to pleas which have not been served on it.Senior advocate Kapil Sibal urged the bench to put on hold operation of CAA and postpone exercise of the National Population Register (NPR) for the time being.The court said it will not grant any stay on CAA without hearing the Centre on the matter."Will pass order on granting any interim relief to petitioner opposing CAA after four weeks," the bench said.The CAA seeks to grant citizenship to migrants belonging to Hindu, Sikh, Buddhist, Christian, Jain and Parsi communities who came to the country from Pakistan, Bangladesh and Afghanistan on or before December 31, 2014.President Ram Nath Kovind gave assent to the Citizenship (Amendment) Bill, 2019 on December 12, turning it into an Act.Several petitions have been filed challenging the constitutional validity of the CAA, including by RJD leader Manoj Jha, Trinamool Congress MP Mahua Moitra, AIMIM leader Asaduddin Owaisi.Several other petitioners include Muslim body Jamiat Ulama-i-Hind, All Assam Students Union (AASU), Peace Party, CPI, NGOs 'Rihai Manch' and Citizens Against Hate, advocate M L Sharma, and law students have also approached the apex court challenging the Act.