More than half of the requests for data that Facebook received from US law enforcement agencies in the second half of 2015 contained a non-disclosure order that prohibited the company from notifying the user whose data was requested, according to a report released today.

Facebook's bi-annual report on global government data requests indicated that there were 19,235 requests in the US during from July to December 2015, up from 17,500 in the first half of the year. The company handed over data in 81 percent of cases.

Worldwide, government requests for account data increased by 13 percent, from 41,214 requests to 46,763. The number of items on the social network restricted for violating local law saw an even more dramatic jump, to 55,827 items, up from 20,568.

There were also up to 499 secret requests made for data under the Foreign Intelligence Surveillance Act (FISA). Companies are prohibited from disclosing detailed figures for FISA requests, and they must delay reporting the aggregate figures for at least six months. FISA requests were the subject of a lawsuit filed last week by the Electronic Frontier Foundation, which claims the Department of Justice is illegally withholding information on surveillance warrants it has obtained under FISA.

In a blog post, Facebook's Deputy General Counsel Chris Sonderby wrote that it does not provide any law enforcement agency access to data unless it determines the request to be legitimate.

"We scrutinize each request for user data we receive for legal sufficiency, no matter which country is making the request," Sonderby wrote. "If a request appears to be deficient or overly broad, we push back hard and will fight in court, if necessary."

Today's report comes a week after Apple released its own government requests snapshot, which also covers the second half of 2015. US law enforcement agencies requested Apple user data 4,009 times, covering more than 16,000 devices. Eighty percent of those requests ended in Apple handing over some customer data.