EMERGENCY services and the military are staging a security exercise at Portsmouth Naval Base on Sunday.
One hundred personnel from the navy, army, Ministry of Defence police and civilian police, fire and ambulance services will take part.
The exercise – between 6.30pm and 9.30pm – involves blank ammunition which is likely to be heard outside the base, particularly along Queen Street, The Hard and parts of Gosport.
Emergency services will be using vehicle sirens within the base.
Naval base security officer Simon Harfield said: ‘The exercise is part of routine security contingency planning and training and is not in response to any specific threat or any increase in the threat level.
‘The aim of the exercise is to practise close multi-agency working, emergency service incident response and to test command and communications.’
This morning the base was due to test its nuclear emergency siren from 9.30am.