Microsoft is seeking permission to disclose "aggregate statistics" about the number of requests for data it receives under the U.S. Foreign Intelligence Surveillance Act, following a similar move by Google earlier this month.

FISA has been thrust into the national spotlight after leaks about the U.S. government's Prism surveillance program, which reportedly provides the National Security Agency with direct access to customer data stored by Microsoft, Facebook, Google and other big technology companies.

Currently, online firms can reveal how many FISA requests they receive only if they lump them together with all other requests from U.S. law enforcement agencies. That obscures the number of FISA requests those companies receive, so Microsoft, like Google before it, has asked for permission to break the numbers out. The FISA Amendments Act (FAA) is the law under which Prism's data collection is carried out.

"To promote additional transparency concerning the government's lawful access to Microsoft's customer data, Microsoft seeks to report aggregate information about FISA orders and FAA directives separately from all other local, state and federal law enforcement demands," Microsoft's lawyers wrote in a motion filed with the Foreign Intelligence Surveillance Court.

Its goal is partly to correct the impression that it provides the government direct access to customer data in its servers, something that has led to criticism of Microsoft and other online firms.

"Microsoft has sought—and continues to seek—to correct the misimpression, furthered by such inaccurate media reporting, that it provides the U.S. government with direct access to its servers and network infrastructure and, thereby, indiscriminately discloses Microsoft users' information to the government," Microsoft's attorneys wrote.

Microsoft has not received permission from the FBI or the Department of Justice to disclose additional figures related to FISA requests in the aggregate, but "there is no statutory basis under FISA or the FAA for precluding Microsoft from disclosing the aggregate data," the company said.

Prohibiting such a disclosure, Microsoft argues, violates its First Amendment right to free speech.

Companies like Facebook, Google and Twitter have also called for greater transparency in disclosure of user data tied to government requests in the wake of Prism's revelations.

Yahoo, for instance, has disclosed the total number of law enforcement requests it receives for customer data, but it too is unable to provide greater transparency around FISA requests specifically.

Facebook has made some requests public in recent weeks, but was still criticized by others for not distinguishing between criminal and security information requests.

Microsoft disclosed its figures for the total number of requests it receives for customer information on June 14. For the last six months of 2012, the company received between 6,000 and 7,000 criminal and national security warrants, subpoenas and orders affecting between 31,000 and 32,000 consumer accounts from U.S. governmental entities, Microsoft reported in a recent blog post.