Amicus claims the bank has reneged on its 2002 promise to keep the "last bank in town" locations open as 15 of the 31 closures will leave certain communities branchless. NAB claims it did not make such a comment.

The closures are part of the second leg of NAB's restructuring programme, announced in May this year, which includes the closure of 60 Clydesdale and 40 Yorkshire branches in the UK.

Amicus says the impact of branch closures on the local communities will be so severe that some customers will have to travel up to 26 miles of rural roads to access full banking facilities.

Mary Alexander, Amicus national officer, says: "UK Banks provide a crucial service to the community and our economic security depends on them. NAB have shelved their corporate responsibilities. These closures will affect some of the most vulnerable areas of the community."