Police warning over stolen detonators

Dozens of detonators used to warn railway workers of approaching trains have been stolen from a car in Sydney's north.

Police say up to 180 Railway Track Signals were stolen from a Sydney Trains employee's car parked in an underground car park in Hornsby overnight on December 27-28.

"The devices pose a safety risk if used incorrectly," police said in a statement on Wednesday.

They say anyone coming across the devices should not tamper with them and if they are offered the detonators for sale, they should contact police immediately.