The U.S. National Security Agency hasn’t infiltrated the servers of Internet companies including Google Inc. and Yahoo Inc., said General Keith Alexander, the agency’s director.

Google, Yahoo and other Internet companies are compelled by court orders to provide the government data for counterterrorism operations and it’s illegal for the NSA to tap directly into their servers, Alexander said at a Bloomberg Government cybersecurity conference in Washington today.

“NSA does collect information on terrorists and our national intelligence priorities but we are not authorized to go into a U.S. company’s servers and take data,” Alexander said.

Alexander was responding to a Washington Post report that the NSA has secretly infiltrated communication links connected to Google and Yahoo servers. The newspaper cited documents obtained from former agency contractor Edward Snowden and interviews with unidentified officials.

The NSA copies data flowing over fiber-optic cables overseas and the agency’s acquisitions directorate sends millions of records every day from Yahoo and Google networks to data warehouses at its headquarters in Fort Meade, Maryland, according to the Washington Post.

The Post cites documents obtained from former NSA contractor Edward Snowden and interviews with officials.

According to a secret accounting dated Jan. 9, 2013, NSA sends millions of records every day from Yahoo and Google internal networks to data warehouses at the agency’s Fort Meade, Md., headquarters. In the last 30 days, the report Wednesday on the Post website said, field collectors had processed and sent back more than 180 million new records – ranging from “metadata,” which would indicate who sent or received emails and when, to content such as text, audio and video.

The NSA’s principal tool to exploit the data links is a project called MUSCULAR, operated jointly with the agency’s British counterpart, GCHQ. The Post said NSA and GCHQ are copying entire data flows across fiber-optic cables that carry information between the data centers of the Silicon Valley giants.

White House officials and the Office of the Director of National Intelligence, which oversees the NSA, declined to comment, the Post said.

In a statement to the Post, Google said it was “troubled by allegations of the government intercepting traffic between our data centers, and we are not aware of this activity.”

At Yahoo, a spokeswoman said: “We have strict controls in place to protect the security of our data centers, and we have not given access to our data centers to the NSA or to any other government agency.”