Pakistan's former military ruler Pervez Musharraf has not appeared in court where he was due to face trial for treason over his imposition of emergency rule in November 2007, charges which he and his legal team dismissed as politically motivated.

The 70-year old's legal counsel filed a plea to exempt him from appearing before court on Wednesday citing security concerns and also requested to adjourn the case for five weeks.

Also on Wednesday, explosives were found close to his home near Islamabad - a third time in the past ten days,

Conviction could mean the death penalty or life imprisonment for Musharraf, who has faced a series of criminal cases since returning from self-imposed exile in March.

Al Jazeera's Imtiaz Tyab reported that the judges would likely not indict him in absentia.

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 and the hearing should not go ahead until rulings have been made on these.

"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 issued late Tuesday.

'Vendetta'

Musharraf on Sunday denounced the treason case as a "vendetta" against him and claimed he had the backing of the military.

The Taliban have made repeated threats to kill the man who led Pakistan into its alliance with Washington's "war on terror", and security for the hearing in Islamabad was tight.

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 treason case was due to start on December 24 but had to be delayed after police found explosives and a detonator on Musharraf's route to court. A second scare came on Monday when more explosives were found on the same road.

It is unclear who left either set of explosives, which were not made up into bombs.