Microsoft has written to the US Attorney General to ask for more freedom to disclose how it handles requests for customer data from national security organisations.
The appeal comes a week after Microsoft reportedly allowed US security agencies to circumvent encryption of Outlook emails and capture Skype online chats, according to leaked documents provided by Edward Snowden.
The world's largest software company said there were "significant inaccuracies" in the media reports last week and asserted it does not allow any government direct or unfettered access to customers' emails, instant messages or data.
In a letter to Attorney General Eric Holder made public today, company lawyer Brad Smith asked Holder to take action personally to permit Microsoft to reveal more about how many security requests it receives and how it handles them.
"We believe the US Constitution guarantees our freedom to share more information with the public, yet the Government is stopping us," said Smith in a blog on Microsoft's website.
He said government lawyers had not responded to a court motion made in mid-June asking for permission to publish the volume of requests it has received.
So far, the US government has restricted what companies can say under about the requests under the highly secret Foreign Intelligence Surveillance Act. Last month, it allowed the disclosure of aggregate numbers of requests for customer data, but not the break down of the split between surveillance and crime-related requests.
Microsoft and Google, along with Apple, Facebook and other US tech leaders are scrambling to assert their independence after leaked documents suggested they gave the US government "direct access" to customer accounts as part of a National Security Agency (NSA) program called PEISM..
"Microsoft does not provide any government with direct and unfettered access to our customers' data," said Smith in his blog. "Microsoft only pulls and then provides the specific data mandated by the relevant legal demand."