Santander has announced the closure of 140 banks – including its branches in Portslade and Shoreham.
The closures are set to affected 1,270 jobs, although Santander said it expects 'to be able to redeploy around a third of those affected'.
It said the number of transactions carried out in Santander branches has fallen by 23 per cent over the past three years, while transactions via digital channels has grown by 99 per cent over the same period.
The Portslade branch on Station Road is set to close on May 23.
Relatesd stories: Shoreham High Street bank to close
The Shoreham bank on High Street is earmarked for closure on May 2.
The closest Santander branch for Portslade will be George Street in Hove and for Shoreham it will be in Chapel Road, Worthing.
Brighton branches in Western Road and London Road will remain open.
Susan Allen, head of retail and business banking, said: “The way our customers are choosing to bank with us has changed dramatically in recent years, with more and more customers using online and mobile channels. As a result, we have had to take some very difficult decisions over our less visited branches, and those where we have other branches in close proximity.
“We will support customers of closing branches to find alternative ways to bank with us that best suit their individual needs. We are also working alongside our unions to support colleagues through these changes and to find alternative roles for those impacted wherever possible.
“We continue to believe that branches have a vital role to play and we will be refurbishing 100 of our branches over the next two years. We are confident that following these changes we will have the right branch network to serve our customers’ changing needs, and we expect the size of our network to remain stable for the foreseeable future.”