Former Pakistan President Pervez Musharraf is also facing accusations of complicity in the slaying of Benazir Bhutto.
Pakistan's Supreme Court has ordered former President Pervez Musharraf to respond to an accusation of treason, a move that could hurt his ambitious bid to win back influence in the country.
Lawyer Iqbal Haider has filed a complaint which states that Musharraf had committed treason when he declared emergency rule while in power, in 2007.
Mohammad Amjad, the coordinator of Musharraf's All Pakistan Muslim League party, said aides would formulate a strategy for dealing with the accusation.
The former army chief returned to Pakistan last month after nearly four years of self-imposed exile to contest a May 11 general election despite the possibility of arrest on various charges and death threats from the Pakistani Taliban.
The Supreme Court barred Musharraf from leaving the country and a representative is expected to appear at a Tuesday hearing.
Musharraf, a U.S. ally in the campaign against Islamist militancy, also faces charges of failing to provide adequate security to former prime minister Benazir Bhutto before she was assassinated in late 2007.
He also faces accusations in connection with the death of a separatist leader in the southwestern province of Baluchistan. He denies any wrongdoing.
The petition to be heard by the Supreme Court on Monday accuses Musharraf of committing treason when he sacked senior judges and declared emergency rule, as he struggled to hold on to power. Critics said he acted unconstitutionally.
The current chief justice, Iftikhar Chaudhry, was embroiled in a confrontation with Musharraf, who removed him from office earlier in 2007 after Chaudhry opposed plans to extend the general's term in office. The judge was later reinstated.
Former Prime Minister Nawaz Sharif, the man Musharraf ousted in a coup in 1999, is seen as the election front-runner.