Another American, Al-Qaeda spokesman Adam Gadahn, was killed, “likely in a separate US government counterterrorism operation.”
“No words can fully express our regret over this terrible tragedy,” the White House said, revealing the previously classified finding. The president “takes full responsibility for these operations.”
Obama is scheduled to make a public address at 1400 GMT (10:00 ET).
The White House identified the hostages killed in the operation against the border compound as US contractor Warren Weinstein and Italian aid worker Giovanni Lo Porto.
Weinstein was snatched after gunmen tricked their way into his home in Lahore on August 13, 2011 shortly before he was due to return home after seven years working in Pakistan.
He later appeared in a video in which, under apparent coercion, he asked the United States to free Al-Qaeda prisoners.
Lo Porto disappeared in January 2012 in Pakistan.
“Analysis of all available information has led the intelligence community to judge with high confidence that the operation accidentally killed both hostages,” the White House said.
“The operation targeted an Al Qaeda-associated compound, where we had no reason to believe either hostage was present, located in the border region of Afghanistan and Pakistan.”
The White House statement did not identify which US agency carried out the operation, which suggests it was carried out by an intelligence service rather than a military unit.
“We have concluded that Ahmed Faruq, an American who was an Al Qaeda leader, was killed in the same operation that resulted in the deaths of Dr. Weinstein and Mr. Lo Porto,” the White House said.
“We have also concluded that Adam Gadahn, an American who became a prominent member of Al-Qaeda, was killed in January, likely in a separate US Government counterterrorism operation,” it added.
“While both Faruq and Gadahn were AlQaeda members, neither was specifically targeted, and we did not have information indicating their presence at the sites of these operations.” -AFP