Microsoft reportedly has allowed the National Security Agency special access to some of its biggest web products -- and potentially tens of millions of users -- as part of the government's wide-ranging surveillance program.
The Guardian reported on the cooperation, citing documents provided by NSA leaker Edward Snowden.
According to the report, the cooperation was forged as part of the NSA's once-secret "Prism" program.
Microsoft let the NSA get around its encryption in order to access the new Outlook.com email service.
It also gave the agency easier access to its cloud storage system and better access to Skype video calls.
The reported cooperation is sure to raise more concerns about the extent of government surveillance, and the intelligence community's involvement with major tech companies -- of which Microsoft is just one.
One document obtained by The Guardian said the FBI and CIA could request copies from the Prism program, saying: "Prism is a team sport!"
The administration, while not commenting in depth on the program, has insisted that all orders are reviewed by a special court and only target individuals believed to be outside the U.S. and not a U.S. citizen.
In a statement to The Guardian, Microsoft said it follows "clear principles" in responding to government demands for information.
"We take our commitments to our customers and to compliance with applicable law very seriously, so we provide customer data only in response to legal processes," the company said.
The NSA said the program operates under a "strict oversight regime."