Pakistan's former military ruler Pervez Musharraf failed to show up for a hearing in the treason case against him on Wednesday, with his lawyers citing security threats. The 70-year-old stands accused over his imposition of emergency rule in November 2007, but he and his legal team have dismissed the charge as politically motivated. Conviction could mean the death penalty or life imprisonment for the ex-dictator, who has faced a series of criminal cases since returning from self-imposed exile last March. His defence team said he could not attend the special treason tribunal on Wednesday because security was inadequate. They also complained that lawyers in the case had been threatened and attacked. The three-judge panel adjourned the hearing to Thursday, asking Musharraf again to appear in person. The delay comes a week after a bomb scare forced the case to be postponed. "He is unable to appear before the court because of security hazards," lawyer Ahmed Raza Kasuri told the tribunal. Another lawyer representing Musharraf, Anwar Mansoor Khan, told the court he was attacked while travelling to Lahore following the last hearing in the case. "How are these proceedings continuing and why are these proceedings continuing when the counsels and respondents have been attacked?" Khan argued in his opening statement. "I was followed by a black Vigo (an SUV) with tinted windows and no number plate. This vehicle hit my car and destroyed it," Khan said. The Taliban have made repeated threats to kill Musharraf, who led Pakistan into its alliance with Washington's "war on terror". He lives under heavy guard at his farmhouse on the edge of Islamabad. Khan also questioned the legality of the court, alleging that Prime Minister Nawaz Sharif had overstepped his legal bounds in forming the special tribunal and that it was he and not Musharraf who should face treason charges. The ex-general's defence team asked the court to summon Sharif on contempt charges for commenting on Musharraf's trial in the media. On the last hearing on December 24, the case was adjourned after explosives were found along the route he was to take to court. On Monday more explosives were discovered on the same road. Potentially destabilising clash Musharraf is the first former army chief to go on trial in Pakistan, setting up a potentially destabilising clash between the government -- which brought the charges -- and the all-powerful military. On Sunday the retired general denounced the treason case as a "vendetta" against him and claimed he had the backing of the military. "I would say the whole army is upset. I have led the army from the front," he told reporters at his farmhouse. "I have no doubt with the feedback that I received that the whole army is... totally with me on this issue." There has been no public comment on the case from the army, but some observers say they are reluctant to have their former chief suffer the indignity of trial in a civilian court. The potential for the case to disrupt Pakistan's delicate civilian-military balance means it will be keenly watched by the US and NATO as they wind down their mission in neighbouring Afghanistan. Pakistan's cooperation and access through its territory is crucial as NATO withdraws military equipment built up over more than a decade of war. Legal battlefield The allegations are the latest in a series of criminal cases faced by Musharraf since he returned to Pakistan in a thwarted bid to run in May's general election. These include murder charges over the assassination in late 2007 of former prime minister Benazir Bhutto. The former commando's lawyers have dismissed the charges as an attempt by the government of Prime Minister Nawaz Sharif, whom Musharraf ousted in a coup in 1999, to settle old scores through the courts. Musharraf spokesman Raza Bokhari said they have filed challenges to the tribunal's authority. "We demand that the unlawfully formed special treason court avoid the label of being called a 'kangaroo court' and suspend its proceedings until the challenges raised by General Musharraf are heard and properly disposed by the superior courts," Bokhari said in a statement late Tuesday. Musharraf's lawyers have urged the United Nations to intervene in what they call a "stage-managed show trial" and have asked London and Washington to "repay their debt" for his support in the wake of the 9/11 attacks.