He said: ''From the outset we were determined to identify people who may have been in the area at the time, including taxi drivers, delivery drivers and people who may have been socialising at private addresses.

BBC: John McMurchie

Allegations that business department officials used private email addresses to seek to circumvent FOI surfaced in an employment tribunal case involving Nominet, which was first reported last month after legal restrictions were lifted.

BBC: FOI, fear and personal emails for public business

According to blogger Brian Krebs, a group of hackers have eviscerated an underground hacker forum by posting database dumps of their private information and communication, including email addresses and private messages sent between users.

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Never post private information like phone numbers or addresses.

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Be sure they understand that personal details like addresses and phone numbers, as well as private photos, should stay offline.

FORBES: On The Web's Edge

Now these companies will compare their lists to the Facebook list and try to match people up by their email addresses and phone numbers (all in a hashed and private way that does not involve an information exchange, says Facebook) so that similar targeting can happen with Facebook ads.

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