A Pakistani court on Tuesday charged former military ruler Pervez Musharraf with the 2007 murder of opposition leader Benazir Bhutto, an unprecedented move against an ex-Army chief.

It is the first time a head of Pakistan’s Army has been charged with a crime, challenging beliefs that the military is immune from prosecution and threatening to fan tensions with civilian institutions.

While murder will be difficult to prove, it may embolden efforts to try Musharraf for treason for seizing power in 1999 and for violating the constitution by sacking judges and imposing emergency rule in 2007. Treason can carry the death penalty.

Musharraf, once the most powerful man in the nuclear-armed state, appeared in court on Tuesday to deny the charges against him.

“He was charged with murder, criminal conspiracy for murder and facilitation for murder,” public prosecutor Chaudhry Azhar told AFP at the anti-terrorism court in Rawalpindi hearing the case.

The 70-year-old retired general’s brief appearance was accompanied by massive security. Musharraf was protected by scores of officers and roads leading to the court were shut down.

Officials had said threats against Musharraf’s life were too severe for him to be charged on August 6 as initially scheduled, although he had appeared in person at an earlier hearing on July 30.

The case was adjourned until August 27 although no date has been set for any trial.

Musharraf's legal team dismissed the charges as “baseless.”

“We are not afraid of the proceedings. We will follow legal procedures in the court,” Musharraf’s lawyer Syeda Afshan Adil told AFP.

Bhutto, twice elected Prime Minister of Pakistan and the first woman premier of a Muslim country, was killed in a gun and suicide attack in Rawalpindi on December 27, 2007.

Musharraf’s government blamed the assassination on Pakistani Taliban chief Baitullah Mehsud, who denied any involvement. Mehsud was killed in a US drone attack in 2009.

In 2010, a UN report accused Musharraf’s government of failing to give Bhutto adequate protection and said her death could have been prevented.

Under Bhutto’s widower, President Asif Ali Zardari, the previous Pakistan Peoples Party (PPP) government initiated proceedings against Musharraf.

In November 2011 the same court also indicted two police officers and five alleged Taliban militants over Bhutto’s death, but none of them has yet been brought to trial.

“There is a long way to go and it will be very, very difficult to prove that he engineered the murder conspiracy or that he was the mastermind,” political analyst Imtiaz Gul told AFP.

“All we have seen is a politically motivated indictment, which may be of no real significance in the long run.”

Nor has the indictment silenced speculation about the possibility of a behind-the-scenes deal that could allow Musharraf to leave Pakistan without going to jail.

For politicians, being hauled before the courts is par for the course in Pakistan. Current Prime Minister Nawaz Sharif was sentenced to life in prison after being deposed by Musharraf in 1999, but was shortly afterwards allowed to go into exile in Saudi Arabia.

Sharif returned to win elections in May, taking over from a PPP government in Pakistan’s first handover of civilian power after several spells of military rule down the years.

Zardari himself, who spent 11 years in jail for alleged corruption, was also indicted in 2003 over the murder of a steel mill chairman, but became president in 2008.

Musharraf on the other hand has enjoyed the comparative luxury of house arrest at his villa on the edge of Islamabad since April after returning from self-imposed exile.

Musharraf has been formally granted bail in two of three cases against him.

Analyst Hasan Askari said the indictment will stoke tensions between the military and civilian institutions of the judiciary and government, but that the Army would play a quiet game.

“They will quietly monitor the situation as to how this case proceeds and to what extent it reflects negatively on the military,” Askari told AFP.

“They are not on the back foot but... They will be concerned about implications of this case for the military.”

Musharraf, who was barred from running in the May elections, is also wanted over the death of Baluchistan rebel leader Nawab Akbar Bugti during a military operation in 2006.

The new government headed by Sharif is investigating the evidence against him for treason, after saying he should stand trial for subverting the constitution.