Punjab government's action comes amidst pressure from the Trump administration to act against terror.
A Pakistani court has asked the Punjab government to explain under what authority it has detained Jamaat-ud-Dawah chief Hafiz Saeed "without a trial".
The government also told the court that it has reasons to believe that Jamaat-ud Dawah and its sister organisation Falah-e-Insaniat Foundation were engaged in activities which can be prejudicial to peace and security.
In their petition, Saeed and four others said the government in light of Interior Ministry's order detained them for a period of 90 days (with effect from January 30) in exercise of powers under section 11-EEE(1) of Anti Terrorism Act 1997.
Saeed and the four men added to the fourth schedule of the ATA were also placed under house arrest on January 30 in Lahore amid an angry uproar from his party and political allies.
The Mumbai attack mastermind had indicated about a week before his arrest that he might launch Tehreek Azadi Jammu and Kashmir (TAJK) to 'expedite the freedom of Kashmir'.
Saeed's three-month detention period was to expire on Sunday night.
Jamaat-ud-Dawah chief Hafiz Saeed's detention may help ease India-Pakistan tension, media reports in Islamabad said on Tuesday even as supporters of the Mumbai attack mastermind launched protests across major cities against the government's decision which they say was taken under pressure from the US and India.