The Supreme Court issued the order against Husain Haqqani pending an investigation into a memo in which he is accused of asking for U.S. help to rein in the Pakistani army, The New York Times reported.
Haqqani, who has denied the allegations -- or any involvement in the May memo -- had to resign this month after he had been summoned home from Washington.
In the controversy, now referred to as "memogate," Mansoor Ijaz, a U.S. businessman of Pakistani origin, had claimed he was asked by Haqqani to deliver the memo to Adm. Mike Mullen, then chairman of the U.S. Joint Chiefs of Staff, seeking American help to prevent a possible military coup in return for Pakistani concessions.
In ordering the travel ban on Haqqani, the high court said a commission led by a former senior investigator would complete its investigation in three weeks, the Times reported. The court asked high ranking officials including army chief Gen. Ashfaq Parvez Kayani and Lt. Gen. Ahmad Shuja Pasha, head of the Inter-Services Intelligence agency, to provide written testimony.
The high court acted on a petition by Nawaz Sharif, former Pakistani prime minister and currently the opposition leader, who claims the memo was likely passed on with the knowledge of Pakistani President Asif Ali Zardari.
The president's office has denied any knowledge of the memo.
The memo scandal points to the depth of mistrust between the powerful Pakistani military, which controls foreign and security policies, and Zardari's civilian government, The Washington Post reported.
The memo, which was unsigned, set off a storm of controversy in Pakistan, whose relations with the United States remain deeply strained, but Mullen has said he did not take it seriously and ignored it.
The Post said a Pakistani parliamentary probe into the memo is also proceeding.
Haqqani said he has no intention of leaving the country and that he had resigned to facilitate a transparent investigation.
Asma Jahangir, Pakistan's noted human rights lawyer, said she would represent Haqqani, the Post reported.