A customer walks past a large screen at the new Apple Visitor Center in Cupertino, California, U.S., November 17, 2017. REUTERS/Elijah Nouvelage

(Reuters) - Apple Inc on Friday issued its twice yearly transparency report on government data requests, showing another sharp increase in U.S. national security-related requests.

Apple said it received as many as 16,249 national security requests affecting up to 8,249 accounts during the second half of 2017. The number of requests rose 20 percent compared with the first half of 2017, when Apple received 13,499 such requests.

But the most recent figures are more than two-and-a-half times higher than the comparable period a year earlier, when Apple received only 5,999 such requests.

Other tech firms also experienced a jump in national security request between the second half of 2016 and the first half of 2017. National security requests to Alphabet Inc’s Google rose 36 percent, to almost 51,000. Similar requests to Facebook Inc nearly doubled, to almost 27,000.

Facebook and Google have not yet reported full numbers of national security requests for the second half of 2017 because both companies break out individual figures for both National Security Letters and requests under the Foreign Intelligence Surveillance Act, or FISA. The FISA numbers are subject to a six-month reporting delay by law. Apple publishes an aggregate number of both types of requests and so is able to report the figures sooner.

Apple also said on Friday that it would start reporting requests from governments to take down apps from its App Store.

Last year, Apple took down virtual private networking apps, or VPNs, from its App Store in China in order to comply with a new Chinese cyber security law. Such apps help users browse the internet more privately and were used to evade Chinese internet censorship rules. Chinese regulators also forced Apple to remove Microsoft Corp’s Skype internet phone and messaging app from the App Store in China.

Apple’s new tracking of app takedown requests starts on July 1, so the data will begin to appear starting one year from now.