NSA, British intelligence secretly tapped into Google, Yahoo cable links, officials say

As part of a long-standing effort to spy on foreign-to-foreign intelligence targets, the National Security Agency and British intelligence services have secretly tapped into Google and Yahoo communications links at collection centers scattered around the world, scooping up metadata on hundreds of millions of accounts — including those belonging to many Americans, NBC News has confirmed.

The agencies collect vast quantities of metadata on Americans who live, work or travel overseas if they use a foreign phone or email address, officials told NBC News.

But officials strongly rebutted a Wednesday report in The Washington Post, citing documents provided to the newspaper by former NSA contractor Edward Snowden, claiming that the program is designed as a "back door" to the records of U.S. users of Google and Yahoo.

"If you've got a U.S. area code, you are filtered out," said a senior U.S. official familiar with the programs — one of which is called "MUSCULAR." That program is operated jointly with the NSA's British counterpart, the Government Communications Headquarters, according to the Post's report.

The official added that the taps do not mean that the content of phone calls or emails is routinely read.

Data collected are not identifiable to any person unless they are judged to be a "valid intelligence target," the official said. If a person is deemed as such, intelligence services would then call up the account, review emails or listen to the content of telephone calls.

"Collecting metadata does not authorize reading emails or listening to calls. It is literally not identifiable," the official said. "It is not until we go back with a particular selector — where we can input it into a system — that it turns into something intelligible."

Officials said the length for which data are kept varies by region.

"We are talking about hard physical collection — on cables," a top official told NBC News.

Another official said congressional committees have been briefed on the tapping programs, adding: "What we are running into is members who did not go to a briefing or did not review the information."

Meanwhile, U.S. officials strongly deny an Italian report that the NSA eavesdropped on the Vatican.

"That is completely not true. It is made up. It did not happen. Categorically untrue," said a top official.

Reuters reported that when asked to comment on the claims in the Italian publication Panorama, Vatican spokesman Father Federico Lombardi said: "We are not aware of anything on this issue and in any case we have no concerns about it."

NBC News' Daniel Arkin contributed to this report.