DUBAI (AFP) - Pakistan's former military ruler Pervez Musharraf is expected to fly home on Sunday after more than four years in exile, defying a Taleban death threat to contest historic general elections.

The 69-year-old ex-dictator says he is prepared to risk any danger to stand for election on May 11, billed to mark the first democratic transition of power in the history of a nuclear-armed country dominated by periods of military rule.

He seized power in a bloodless coup as army chief of staff in 1999 and left the country after stepping down in August 2008, when Mr Asif Ali Zardari was elected president after the murder of his wife, former prime minister Benazir Bhutto.

Mr Musharraf is expected to arrive in Karachi at around 12:35 pm (3.35pm Singapore time) on a scheduled flight from Dubai and make his way to the tomb of Mohammad Ali Jinnah, the father and first president of Pakistan, before holding a public rally.

But after the Pakistani Taleban threatened to dispatch a squad of suicide bombers to assassinate Mr Musharraf, police said they had withdrawn permission for Mr Musharraf to hold the rally for his All Pakistan Muslim League (APML) party.

Karachi, a city of 18 million, is already in the throes of record political and ethnic violence. On March 3, a huge car bomb killed 50 people in a mainly Shiite Muslim area of the city.

"There are security concerns," police official Tahir Naveed told AFP. "The permission given to the organisation to hold a rally has now been cancelled.

The organisation has been informed of the decision. We hope they will cooperate." But Aasia Ishaq, APML central information secretary, said the party would still go ahead and hold the rally "at any cost".

"We are going to have the meeting tomorrow (Sunday) despite the Taliban threat," she told AFP.

Mr Musharraf on Saturday admitted there was a security risk and expressed concern for his supporters, but said he personally was not frightened.

"I don't get scared... by such kind of threat," he told reporters. As ruler of Pakistan, he escaped three Al-Qaeda assassination attempts.

He became a prominent target for Islamist extremists after becoming a key US ally in the "war on terror" after the 9/11 attacks.

In July 2007, he ordered troops to storm a radical mosque in Islamabad. The operation left more than 100 people dead and opened the floodgates to Islamist attacks in Pakistan, which have killed thousands since then.

When Ms Bhutto returned to Karachi from eight years in exile on October 18, 2007, bomb attacks killed at least 139 people in what remains the deadliest single terror attack on Pakistani soil.

She was later assassinated in a gun and suicide attack at an election rally in Rawalpindi on Dec 27, 2007. Her son, Bilawal Bhutto Zardari, who is chairman of the Pakistan People's Party, has accused Mr Musharraf of her murder.

Mr Musharraf is wanted by the courts over Ms Bhutto's death, the 2006 death of Akbar Bugti, a Baluch rebel leader in the southwest, and for the 2007 sacking and illegal arrest of judges.

Human Rights Watch called on the Pakistani government to hold Mr Musharraf accountable for widespread and serious human rights abuses under his rule.

"Only by ensuring that Musharraf faces the well-documented outstanding charges against him can Pakistan put an end to the military's impunity for abuses," said Ali Dayan Hasan, Pakistan director at HRW.

Under Mr Musharraf's watch, the military and intelligence agencies committed widespread rights violations, including the enforced disappearances of thousands of political opponents and tortured hundreds of terrorism suspects, HRW said.

On Friday a court in Karachi granted him protective bail for at least 10 days on charges of conspiracy to murder and illegally arresting judge.

But analysts say there is a real danger to his life, which outweighs his political future in a country where his power base his evaporated.

"I don't know why he is taking the risk when he has not a bright future in Pakistan," said retired lieutenant general Talat Masood.

Last year he delayed a planned homecoming after being threatened with arrest. Commentators believe he can only secure, at most, a couple of seats at the polls.