"Zakiur Rehman Lakhvi filed a petition in the Islamabad High Court, challenging his detention under Maintenance of Public Order," Lakhvi's counsel Raja Rizwan Abbasi said.
"Legal requirements have not been fulfilled in the detention of Lakhvi. Besides, the legal grounds the government has cited in the matter are not maintainable," he said.
The court will fix the date for hearing of the case on Monday.
Islamabad Anti Terrorism Court Judge Kausar Abbas Zaidi on December 18 had granted bail to Lakhvi citing lack of evidence against him in the Mumbai attacks case, but before he could be released from jail, the government detained him for three more months under Public Maintenance Order in Adiala Jail where the trial is being held.
Lakhvi on Wednesday had submitted an application with the Pakistan government seeking an end to his detention under MPO.
Abbasi said the government rejected Lakhvi's plea seeking his release from detention under MPO earlier this morning.
"We had earlier made it clear that if the government did not entertain our request to free Lakhvi we would move the high court and challenge his illegal detention," he said.
Asked about how Lakhvi filed the petition in the Islamabad high court as the superior courts are closed for a two-week winter break till January 8, Abbasi said, "Detention is a matter of urgent nature and the courts take such cases during the holidays as well."
Meanwhile, the government has so far failed to file a plea challenging bail to Lakhvi as the courts closed for a two-week winter break, citing that the judge has not released the copy of the order.
The decision to grant bail to Lakhvi, 54, drew sharp criticism from India and surprised many for its timing; just days after Taliban massacred 148 people, mostly school children, in Peshawar.
Lakhvi and six other accused -- Abdul Wajid, Mazhar Iqbal, Hamad Amin Sadiq, Shahid Jameel Riaz, Jamil Ahmed and Younis Anjum -- have been charged with planning and executing the Mumbai attacks that took place on November 26, 2008, and left 166 people dead.
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