The Washington Post published on Saturday a set of slides regarding PRISM, revealing more details about the National Security Agency's controversial surveillance program and how it operates.

The new slides, which come nearly a month after former NSA employee Edward Snowden leaked classified documents to the press about the program, appear to confirm that the NSA and FBI have the ability to perform real-time surveillance of e-mail and stored content.

The slides also seem to contradict denials from tech companies such as Google, Apple, Yahoo, and Microsoft about their level of participation in the program. The program "uses government equipment on private company property to retrieve matching information from a participating company, such as Microsoft or Yahoo and pass it without further review to the NSA," The Washington Post reported.

Another slide shows how the data is collected by an FBI "interception unit" installed at the companies involved and then passed on to "customers" at the NSA, FBI, or CIA. "Depending on the provider," the program allows the NSA to "receive live notifications when a target logs on or sends an e-mail," as well as "monitor a voice, text or voice chat as it happens."

The new data also reveals when each company allegedly joined PRISM. Microsoft was the first company to join the program in September 2007, according to one slide, followed by Yahoo about six months later and Google in early 2009, according to one of the slides. Apple was the last to join the program last October.

Google, Apple, Yahoo, Microsoft, Facebook, and other Internet companies have been left reeling after a pair of articles earlier this month alleged that they provided the NSA with "direct access" to their servers through a so-called PRISM program. Subsequent reporting by CNET revealed that this was not the case, and the Washington Post backtracked from its original story on PRISM.

Legally barred from discussing its participation in the program, Google and Microsoft have petitioned a secretive U.S. surveillance court to lift a gag order prohibiting it from disclosing more information about government requests it receives for customer data. To date, the companies have released only totals that combine legal requests made under the Foreign Intelligence Surveillance Act with other related to criminal investigations involving fraud, homicide, and kidnapping, making it impossible to determine how many FISA requests they have received.

CNET has contacted the Justice Department for comment on the new slides and will update this report when we learn more.

In another revelation, the U.K.-based Guardian reported Sunday that "top secret" documents show that the U.S. intelligence community is spying on European Union diplomatic missions. The documents, leaked by the NSA whistleblower Edward Snowden, lists 38 "targets" and details surveillance methods used against each, including bugs implanted on communications equipment and taps on communications cables.