Microsoft said on Thursday it had received at least a thousand surveillance requests from the U.S. government that sought user content for foreign intelligence purposes during the first half of 2016.

According to Microsoft's biannual transparency report, the amount was more than double what the company said it received under the Foreign Intelligence Surveillance Act (FISA) during the preceding six-month interval, and was the highest the company has listed since 2011, when it began tracking such government surveillance orders.

Microsoft said it received between 1,000 and 1,499 FISA orders for user content between January and June of 2016, compared to between 0 and 499 during both January-June 2015 as well as the second half of 2015.

The number of user accounts impacted by FISA orders fell during the same period, however, from between 17,500 and 17,999 to between 12,000 and 12,499, according to the report.

The U.S. government only allows companies to report the volume of FISA requests in wide bands rather than specific numbers.

Parts of FISA will expire at the end of the year, unless U.S. lawmakers vote to reauthorize it.

Other technology companies, including Twitter and Yahoo have also disclosed national security letters in recent months under a transparency measure of the USA Freedom Act that was enacted into law by the U.S. Congress in 2015.