Police have adopted new stop and search powers in Sussex in the wake of the London bombings.
Previous powers meant officers had to have cause or suspicion to stop and search someone but the new emergency powers mean police can now do so without reason.
British Transport Police were the first to adopt the powers after last Thursday's bombings and now other forces are introducing them.
The powers are contained within the Anti-Terrorism Act but each constabulary wanting them has to obtain the approval of the Home Secretary.
Charles Clarke granted approval for Sussex on Sunday.
Geoff Williams, Sussex Assistant Chief Constable, said the main reasons for adopting them were because of the county's extensive rail and bus networks and because Brighton and Hove is only 70 days away from hosting the Labour Party conference.
Mr Williams said: "Our officers have been asked to use this new power with discretion.
"This does need to be exercised with care. I believe, given the current circumstances, this is a sensible use of the powers."
Mr Williams has also authorised armed police to patrol sensitive sites in Sussex including rail stations.
He said they were designed to increase police visibility, to help deter acts of terrorism and to provide reassurance.
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