Updated 6:15 p.m. ET
WASHINGTON National Intelligence Director James Clapper is apologizing for telling Congress earlier this year that the National Security Agency does not collect data on millions of Americans.
Clapper was asked during a hearing in March by Sen. Ron Wyden, an Oregon Democrat on the Intelligence Committee, if the NSA gathered "any type of data at all on millions or hundreds of millions of Americans."
At first, Clapper answered definitively: "No."
Pressed by Wyden, Clapper changed his answer. "Not wittingly," he said. "There are cases where they could inadvertently perhaps collect, but not wittingly."
In a letter to Senate Intelligence Committee Chairwoman Dianne Feinstein, D-Calif., Clapper says his answer was "clearly erroneous."
"My response was clearly erroneous - For which I apologize," Clapper wrote. "While my staff acknowledged the error to Senator Wyden's staff soon after the hearing, I can now openly correct it because the existence of the metadata collection program has been declassified."
Last month, the White House came to Clapper's defense after Wyden blasted the intelligence official for failing to give "straight answers" on the government surveillance of Americans.
President Obama "certainly believes that Director Clapper has been straight and direct in the answers he's given" Congress, White House spokesman Jay Carney said, adding that Clapper has been "aggressive in providing as much information as possible to the American people, to the press."
Wyden spokesman Tom Caiazza said Tuesday that when Wyden staffers contacted Clapper's office shortly after the hearing, his staffers "acknowledged that the statement was inaccurate but refused to correct the public record when given the opportunity."
"Sen. Wyden is deeply troubled by a number of misleading statements senior officials have made about domestic surveillance in the past several years. He will continue pushing for an open and honest debate," Caiazza said.
Leaks by NSA systems analyst Edward Snowden have revealed the NSA's sweeping data collection of U.S. phone records and some Internet traffic every day, though U.S. intelligence officials have said the programs are aimed at targeting foreigners and terrorist suspects overseas.Snowden is believed to be in a Moscow airport transit area, seeking asylum from one of more than a dozen countries.
Since the revelations, the Obama administration has said the leaks have caused damage to national security, including tipping off al-Qaida and other terrorist groups to specific types of U.S. electronic surveillance.
But under pressure from lawmakers and privacy activists, the administration took the extraordinary step of declassifying many of
the details surrounding the surveillance programs and how they work, to explain to Americans that NSA is not spying directly on them, which would violate its charter.