Microsoft moved to address persistent concerns that it has helped the US government gather customer information, saying it doesn't provide direct access to e-mails, instant messages or Skype calls and refuses to grant agencies the ability to break its encryption.

In a letter today to US attorney general Eric Holder, the company asked for permission to share more information on its communication with government agencies, saying it has a constitutional right to do so. Microsoft said such permission has been delayed and asked Mr Holder for personal help. Microsoft and technology companies Apple, Facebook and Yahoo! have come under scrutiny since a former US National Security Agency contractor said publicly last month that the NSA is collecting user data.

Microsoft said that while it’s limited in what it can disclose about communications, the company doesn’t grant access to servers and only provides governments with specific information about requests. That includes data from its SkyDrive cloud service.

“We do not provide any government with the ability to break the encryption, nor do we provide the government with the encryption keys,” Microsoft general counsel Brad Smith said in a blog post today. “When we are legally obligated to comply with demands, we pull the specified content from our servers where it sits in an unencrypted state, and then we provide it to the government agency.”

Brian Fallon, Mr Holder’s spokesman, didn’t have an immediate comment on the letter.

Last week, the Guardian reported that Microsoft has helped the NSA get around the company’s own encryption, citing documents obtained by the newspaper. Microsoft, the world’s biggest software maker, also said that when it receives a request for information held by a corporate customer, the company redirects the government to the client, unless prohibited from doing so. The company said it has never provided information on a corporate customer for national security purposes and complied with four requests in 2012 related to criminal law enforcement.

Since the NSA documents were leaked, Microsoft has held talks with the Justice Department, Federal Bureau of Investigation and others in the intelligence community about which issues the company can publicly address, Mr Smith wrote in the letter.

Bloomberg