Residents are being warned to keep their windows closed and avoid the area as emergency services tackle a fire at Shoreham Port this morning (March 15).
The fire at a building merchants along the seafront in Portslade is also causing traffic delays in the area.
East Sussex Fire Service was called at 8.44am today (March 15) to the fire at Chandlers Building Supplies on Basin Road North.
A fire service spokesperson said: "At 8.44, firefighters were called to a fire at a building merchants on Basin Road, Portslade. We currently have 6 appliances in attendance. Please avoid the area if possible."
Brighton and Hove Police said: "We are advising motorists to avoid the Kingsway area from #Portslade as it is closed due to a fire in Basin Road North.
"There is a diversion from St Keyna Avenue to Wish Road. Residents who live in the Kingsway area should keep their windows closed due to the smoke."
In an update this morning at 10.10am, East Sussex Fire and Rescue Service said: "Crews are responding to a serious fire in Portslade at Chandler Building Supply’s, Basin Road, North Portslade. There are now eight fire appliances in attendance at the scene along with two aerial ladder platforms and a water bowser.
"The fire is in a store room of the builders merchants and the building is well alight. The building is approx 13m x 25m. Crews are currently tackling the fire.
"Due to large volumes of smoke in the Portslade, boundary area, the public are advised to avoid the area. Sussex Police have also implemented road closures in the area and traffic is busy.
"Six fire appliances responded initially from Hove, Shoreham, Roedean and Newhaven along with a further two from Preston Circus.
"A further two fire appliances have now been dispatched from Lewes and Newhaven along with two aerial ladder platforms from Preston Circus and Worthing along with a water."
A statement from Chandlers Building Supplies said: "Firefighters are currently at the Brighton branch of builders merchants, Chandlers Builders Supplies located at Basin Road North, Aldrington Basin, Portslade.The Chandlers Building Supplies Brighton branch will be closed today.
"The fire service is working at getting the situation under control. It appears that the fire started early this morning. We do not know any further details at this stage. Most importantly, nobody has been harmed or injured.
"Chandlers Building Supplies is a family-owned builders merchants and roofing supply specialist with 13 branches throughout London, the South East and the West Midlands."