Pakistani security agencies investigating last week's deadly suicide attack on former Premier Benazir Bhutto have held at least 15 people for questioning, a police official said Wednesday.
Some of those held were wounded in Thursday's attack on Bhutto's homecoming procession and were picked up from local hospitals. None are currently being treated as suspects, a police investigator told The Associated Press.
The investigator, who spoke on condition of anonymity because he was not authorized to speak to the media, said around 15 or 16 people were being held. He would not say exactly where or share information about their identities.
A second police investigator confirmed that a number of people were being questioned.
The attack rocked Pakistan's largest city, killing about 136 people, as Bhutto marked her return from an eight-year exile.
Authorities say it was likely carried out by two suicide bombers, and have released a picture showing the head of one of the bombers but have yet to identify him.
Security in the city remains high as Bhutto revealed on Tuesday she had received a new death threat. She said her lawyer received a letter from an unidentified "friend of al-Qaida" threatening to slaughter her "like a goat."
The authenticity of the letter could not be confirmed. Bhutto said the writer claimed to be the "head of the suicide bombers and a friend of al-Qaida and Osama bin Laden."
Speaking at her heavily guarded Karachi residence, Bhutto said her opponents "are petrified that the Pakistan People's Party will return (to power) and that democracy will return."
Bhutto, whose two governments between 1988 and 1996 were toppled amid allegations of corruption and mismanagement, has returned to contest parliamentary elections due in January, after months of talks with President Gen. Pervez Musharraf that could see them working side-by-side in the next government. Both voice strong concern over rising religious extremism in Pakistan.
In a sign of that trend, Pakistan's army said Wednesday it has sent 2,500 troops into a remote valley in the country's northwest to combat followers of a militant cleric, Maulana Fazlullah, calling for Taliban-style rule.
Meanwhile, a provincial High Court acquitted a man convicted of involvement in a deadly bomb attack on a Karachi Shiite mosque in May 2004, killing more than 20 worshippers. Gul Hasan had been sentenced to death, but the court agreed with his lawyer's claim that the convictions were flawed, his lawyer Mohammed Farooq. He had already been acquitted over a bombing of another mosque that killed a similar number.