ISLAMABAD/KARACHI " The US Embassy in the capital and its Consulate in Karachi have received two separate envelopes containing unknown white powder on night between Thursday-Friday. Confirming the reports, US Embassy spokesman Lou Fintor said that tests were being conducted on the substance. But he declined any comment on whether or not any embassy staffers had become sick or were under observation. Fintor said that the two outposts leading to the embassy would remain open and there was no plan to close them. He further said that a very small number of people had touched the envelopes, and that nobody was showing any signs of illness. The mysterious event has sparked a security scare in the US Embassy. Officials also declined to comment on the origin of envelopes or to whom they were addressed. It may be recalled that after 9/11 attacks, there had developed a worldwide panic of Anthrax envelopes ostensibly linked to Al-Qaeda and Saddam Hussain's Weapons of Mass Destruction (WMDs) by the US government. The envelopes of white powder in 2001 had inflamed a sense of fear and uncertainty across the world particularly in America. Those Anthrax virus polluted letters, usually carried, "Death to America Death to Israel Allah is great slogans. Meanwhile, the US authorities initiated a probe into the incident. Talking to The Nation, Louis Fintor, a US embassy spokesman, confirmed that the American diplomatic outposts had received suspicious envelopes. He said there were much better ties between Pakistan and the US but, he added, he could not comment on whether the Pakistani and Americans agencies were mutually investigating the matter or US was taking assistance form Pakistani authorities to probe that suspicious envelopes. "Despite all this, let me clear one thing that the US has been taking up the issue very seriously and substances are being probed," he said, adding that the US Embassy in Islamabad and the US Consulate Karachi remained open and were continuing their normal working. When contacted, Capital City Police Chief Wasim Ahmed said that they (US) had good laboratories and experts to investigate the substances. They might have contacted the Crime Investigation Department (CID) but they did not directly consult with the city police, he added. The CCPO further said that it should first be established whether the suspicious envelopes were containing anthrax or any other substance. Agencies add: Fintor said tests were being conducted on the envelopes, which were opened at the US Consulate in Karachi on Thursday, and US Embassy in Islamabad on Friday, he told AFP. Fintor would not specify what kind of substance was involved or disclose where they had been mailed from. "There are no reports of any illnesses among the very small group of people that dealt with the incidents," he added. "They followed established protocol for handling auspicious articles. We take these type of threats seriously whether they are a hoax or not." The envelopes were sent to the US Embassy in Islamabad and the US Consulate in Karachi on Thursday and Friday.