Lloyds Banking Group has told staff it will be closing 49 branches, resulting in 99 job losses.
The branch closures will be taking place across the Halifax, Bank of Scotland and Lloyds Bank chains, according to Unite the Union.
The union said staff had been informed of the branch closures today (29 November) and it warned that the news would undermine the company's plans for growth.
Rob MacGregor, Unite national officer said: “Lloyds Banking Group needs to halt this unnecessary bank branch closure program.
"Local communities are making it clear that the closure of their local branch excludes customers who cannot use digital means to conduct their financial transactions.
“Having returned to profitability LBG needs to stop ignoring its corporate social responsibilities. Just over six months ago the bank announced the closure of 100 branches and today another 49 branches.
"The news today will not be welcomed by staff or the customers left with no access to local banking."
In a statement Lloyds Banking Group said that even with these closures around 95 per cent per cent of Lloyds customers and around 90 per cent of Halifax and Bank of Scotland customers would have a usable branch within five miles of their home.
A spokesman said: "Customers are increasingly choosing to use digital and mobile channels for their everyday banking needs.
"As a consequence, the number of customers visiting some of our branches has declined in recent years. In response to this, we have confirmed the locations of some branches which will close next year across Lloyds Bank, Halifax and Bank of Scotland.
"Branches remain a key part of the service we offer to customers, and we continue to make significant investment in revitalising our network, shaping it to their needs."