Officers cordoned off part of the market town after the alarm was raised. A Tesco store close to where the object was discovered has reportedly been put on lockdown and shops in the area have closed their doors as a precautionary measure. Fareham Police said officers specialising in the safe disposal of explosives were assisting with the operation.
The force tweeted: "We are currently dealing with a police incident on West Street, Fareham.
"Police are erecting a 100m cordon from Poundland on West Street & advise people to keep away from the area at this time."
They added: "This is a joint emergency service response, including explosive ordnance disposal team (EOD) following the discovery of a suspicious package.
"The cordon remains in place at this time and this will have an impact on transport links including buses.
"Fareham Shopping Centre has also been closed as a precaution, as public safety is paramount."
Specialist bomb disposal officers are using an X-ray machine to examine the suspicious device, according to reports.
No injuries have been reported.
A video posted online showed crowds of curious onlookers gathered near a police cordon.
Express.co.uk has contacted stores in the area for more information.
First Bus Portsmouth announced changes to its routes due to the closure of the bus station in Fareham.
They said: "Due to the closure of Fareham Bus Station because of an ongoing incident, all change-overs will take place on the A32, Fareham, before the Market Quay Roundabout."
Some people took to social media to express their concern about the incident.
One man siad: "Worrying news emerging from Fareham this afternoon.
"Thoughts with Fareham Police, JSEODOC and all responding."
He was referring to Joint Service EOD, which comprises both military and civil bomb disposal experts.
More to follow...