Nine Bank Of Ireland branches in Cork are to close, as the bank reduces its network in the Republic by 88 outlets.
It follows a deal with An Post to offer customers access to banking services at more than 900 locations.
Bank of Ireland said the majority of the branches that are closing are self-service locations which do not offer a counter service.
The Cork branches set for closure are Cork Institute of Technology, Glanmire, Bantry, Cobh, Dunmanway, Kanturk , Millstreet, Mitchelstown and Youghal.
Senator Tim Lombard described West Cork as badly hit by the announcement, with the closure of the Dunmanway and Bantry branches.
"Dunmanway is not a tourist town, it is a business town," he said.
"It is a real shame."
He continued: "Bantry's nearest Bank of Ireland branch now will be in Skibbereen or Kenmare. That has left an area which in geographical terms is almost as big as a county without a Bank of Ireland banking branch."
East Cork TD James O'Connor told The Echo he is "disgusted with Bank of Ireland's decision to strip customers of vital local branches in Youghal, Cobh and Mitchelstown.
"There must be a proper explanation provided as to why these closures were necessary," he added.
Meanwhile, Independent Councillor Ger Keohane said of the imminent closure of the Glanmire Bank of Ireland branch: "It's disappointing. It provided a very good service down in Glanmire.
"People got their money and might have spent a few bob in local coffee shops and whatnot and do their shopping in Supervalu.
"It's just going to add more and more pressure on the Post Office and it's causing a big inconvenience to people."
He also highlighted the potential job losses being faced by staff at the branches affected.
"Let's remind people that we the people had to bail out the banks. It's just a real disappointing announcement."
Bank of Ireland is to close 103 branches across the island of Ireland.
The bank is to shut 88 outlets in the Republic, reducing its network from 257 to 169, while in Northern Ireland the network will be reduced by 15 from 28 to 13.
The closures come after Ulster Bank's parent company, NatWest, last month announced that it was withdrawing Ulster Bank from the Irish market.
Bank of Ireland group chief executive Francesca McDonagh said: "Technology is evolving and customers are using branches less, year on year on year.
"Covid-19 has accelerated this changing behaviour and we've seen a seismic shift towards digital banking over the past 12 months."
Ms McDonagh said Bank of Ireland has reached a "tipping point" between online and offline banking, with its mobile app the most popular way to bank. In contrast the number of people visiting branches has "sharply declined" and is now just over half of what it was in 2017.
"We know news like this can cause concern for some customers and for the communities that we serve," she added.
"We're not making these changes immediately - no branches will close in the next six months.
"That allows us to ensure the An Post partnership is up and running before any branches close, and gives us time to communicate fully with all our customers about every option available to them online, in a nearby BOI branch, or at a local post office."