ISLAMABAD, Dec. 23 (Xinhua) -- A court in Pakistan on Monday rejected a petition by former President Pervez Musharraf against a special court constituted to try him for high treason, lawyers said.

The special court is set to initiate formal high treason proceedings against Musharraf in Islamabad on Tuesday for abrogating the country's constitution when he had imposed emergency rule in 2007.

Prime Minister Nawaz Sharif last month approved the selection of three judges for the special court, which has summoned Pervez Musharraf to appear on Dec. 24.

Musharraf had challenged formation of the special court, nomination of its judges by the prime minister and a special prosecutor in the Islamabad High Court. His lawyers had argued that the former military president had imposed emergency rule as the army chief and that he should be charged under army's law and tried in a military court.

Musharraf's defense lawyer Mansoor Ali Khan told the court that the prime minister has nominated those judges for trial of his client who had refused to take the oath under Musharraf's Provincial Constitutional Order and that the trial would not be fair.

Khan also challenged the appointment of the special prosecutor Akram Sheikh as the prosecutor had himself requested the prime minister to assign the duty to him. He said Musharraf's legal team cannot expect fair trial by the special court, requesting the Islamabad High Court to stop the special court from proceedings.

However, the Islamabad High Court's judge Riaz Muhammad Khan rejected the petition and ruled that the special court is under the law and that it can initiate the trial.

The government has initiated the high treason case against the former military president for suspension of the constitution when he had imposed emergency rule in November 2007. Legal experts say the charges carry death penalty or life imprisonment.

Last week a panel of Musharraf's lawyers in London appealed to the United Nations to intervene and stop the trial of the former president in high treason charges. They also sought help from the United States, Britain and Saudi Arabia.

Musharraf told private Pakistani television channels last Thursday that he will apologize for some of his actions if that had harmed the people. However, he said he had taken all decisions in the interest of the country.

It is the first time in Pakistan's 66-year history that a former military leader will be tried for high treason.

Musharraf had taken over in a bloodless coup when he had dismissed then government of Prime Minister Nawaz Sharif in 1999.

The 69-year-old former army chief currently lives in his farmhouse in Islamabad after he got bails in three high profile cases including the 2007 assassination of the former Prime Minister Benazir Bhutto.

Musharraf, who had resigned in 2008 and had gone into exile, returned to the country in March this year to take part in parliamentary elections. However, a court disqualified him from standing in the May elections.