Research In Motion was threatened with reprisals Tuesday if it released encrypted communications of its British Blackberry users to help British police quell days of violent looting.A group or person identified only as Team Poison hacked RIM\'s official blog and posted a message online warning the Canadian firm against assisting police in identifying rioters and looters thought to have used Blackberry instant messaging to coordinate attacks in London and other cities engulfed by rioting.\"If you do assist the police by giving them chat logs, GPS locations, customer information and access to peoples\' BlackBerry Messengers, you will regret it,\" said the post. The message went on to say a hacked database containing the names, addresses and phone numbers of RIM employees would be made public and \"passed onto rioters\" if RIM did not comply.\"Do you really want a bunch of angry youths on your employees doorsteps?\" it warned. \"Think about it.\"RIM officials in Britain offered Monday to assist authorities \"in any way possible.\" Most of the trouble in Britain has flared up in the evenings since the violence erupted in north London on Saturday following the fatal shooting of a police suspect. There was more to come on Tuesday night as hundreds of masked youths rampaged through the center of Manchester, smashing windows and going on a looting spree as the worst riots for decades in Britain spread to a new city on a fourth night of unrest.