Facebook, which recently opened a massive data centre in Sweden, said it had "aggressively" protected its user data from the US government
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US spy leaks

Profile: Edward Snowden
Q&A: Prism and privacy
Beware the humble contractor
What spooks know about you
Facebook received 9,000-10,000 requests for user data from US government entities in the second half of 2012.

The social-networking site said the requests, relating to between 18,000 and 19,000 accounts, covered issues from local crime to national security.

Microsoft meanwhile said it received 6,000 and 7,000 requests for data from between 31,000 and 32,000 accounts.

Leaks by a former computer technician suggest the US electronic surveillance programme is far larger than was known.

Internet companies - including Facebook, Google, Yahoo, Apple and Microsoft - were reported last week to have granted the National Security Agency (NSA) "direct access" to their servers under a data collection programme called Prism.