A Pakistani court issued an arrest warrant for Musharraf last year over allegations he played a role in the attack, which he has denied. Arrest warrants were also issued for two senior police officials accused of negligence in the assassination. Prosecutors accused one of the officials of failing to provide proper security for Bhutto and the other of cleaning the crime scene before evidence could be collected.
A U.N. investigation into the assassination said it could have been prevented and blamed all levels of government for failing to provide adequate security. It also accused intelligence agencies and other officials of severely hampering the investigation into those behind her murder.
The attack on the tribal police posts before dawn Thursday took place in the town of Darra Adam Khel in Khyber Pakhtunkhwa province, government officials said. The town is located near Pakistan's tribal region, the main sanctuary for Taliban militants in the country.
Security forces have launched an operation to try to recover the 21 missing policemen, said the officials, speaking on condition of anonymity because they were not authorized to talk to the media.
No group has claimed responsibility for the attack, but suspicion will likely fall on the Pakistani Taliban.
Associated Press writer Riaz Khan contributed to this report from Peshawar, Pakistan.
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