Pakistan's former president, Pervez Musharraf, on Monday pleaded not guilty to five counts of treason, in the latest chapter of a long-running drama between the country's increasingly assertive judiciary and its former military ruler.

Musharraf faces the death penalty if convicted of the charges over his suspension of the constitution and imposition of emergency rule in 2007, when he was trying to extend his rule as president.

Judge Faisal Arab, who heads the special panel of three judges trying the case, rejected a defence plea for additional time.

Musharraf stood ramrod straight and replied "Not guilty" to each charge.

"I would like to ask where is the justice for me in the Islamic republic of Pakistan ... I have only given to this country and not taken anything," Musharraf said.

"I prefer death to surrender."

The case is being closely watched for any impact on the relationship between Pakistan's three power centres - the historically powerful military, an increasingly independent judiciary and the civilian government, led by Prime Minister Nawaz Sharif.

Some observers are concerned that the trial could anger the army, which has ruled Pakistan for more than half its history since independence in 1947.

Musharraf has told reporters the whole army supported him, though the military leadership has given no indication that it might intervene in the trial.

Musharraf's lawyer later asked the court for permission for his client to visit his sick mother in Dubai. The former military ruler is currently under house arrest. The court promised to rule on the request during the day's proceedings.

Musharraf's trial began last November, but faced repeated delays. First he refused to appear. Then a series of explosive devices was found planted along his route.

On January 2, he was rushed to hospital when he suffered chest pains on the way to court.

Musharraf's lawyers have challenged the court's jurisdiction, saying it was inherently biased because the judiciary had helped lead popular protests that led to his resignation in 2008.

They argue that Musharraf cannot receive a fair trial under the government of Sharif, who won landslide elections a year ago. Musharraf deposed Sharif in a coup in 1999.