It appeared to be the first reported case of anthrax sent to a government office in Pakistan, a nuclear-armed country of 174 million that is battling a Taliban insurgency and where Al-Qaeda chief Osama bin Laden was shot dead.
"The parcel containing anthrax powder was sent last month, about 20 days ago. After the laboratory test confirmed that the parcel contained anthrax we registered a case against unknown people," said police officer Hakim Khan.
There was no immediate confirmation from the prime minister`s house, which lies in the heavily secured secretariat area of the capital Islamabad.
The parcel was posted from the Jamshuru district in southern province Sindh, the capital of which is Karachi -- Pakistan`s biggest city and the port used by the United States to ship supplies to troops fighting in Afghanistan.
"We have sent a police team to investigate it and to find the culprits there," said Khan, a police officer in the secretariat district. (*)