Loud noise is expected as Fawley Refinery tests its public warning system.

Residents will hear a ‘two-tone warble’ of the activation sound on October 3 from 2.30pm and 7pm.

ExxonMobil said the noise is set to last for one minute.

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The ‘all clear’ sound will be continuous throughout this time.

No action is required by residents while the testing is ongoing.

The COMAH alarm is tested on the first Tuesday in October each year.

A statement said: "The COMAH alarm has never been sounded in earnest in 70 years of operations."

It added: "Approximately 200 dedicated responders undergo ongoing and thorough training to ensure a world-class emergency response. In addition, our response teams work closely with Hampshire Emergency Planning and the services to safeguard, our employees, contractors, neighbours, environment and facilities.  

"Fawley’s emergency response teams routinely take part in training and simulated scenarios to ensure the most appropriate preparation and coordination."