Zurich Municipal has warned that professional thieves are targeting computer systems worth more than £250,000 in raids on public service organisations.

The insurer has written to local authorities, universities and other public sector operations to impress upon them the need for efficient and robust physical and electronic security.

Zurich Municipal loss control manager John Robinson said the thieves targeted Sun Microsystems servers and components.

He said in some instances thieves took eight minutes to enter premises, steal equipment and escape.

"These are highly professional thieves and the highest possible standards of security are required if they're to be deterred," Robinson said.

"With some systems worth £250,000 or more, and staff safety a real concern, a small investment in security is worthwhile."

He said security could include the installation of entrapment devices, intruder alarms and "smoke cloaks" which increase the time needed to remove the equipment. Added security could be achieved if system packaging were not left on display in public places while awaiting disposal.