The Glasgow-based lender is planning to shut 79 branches, the largest closure programme in its history, the union said.

"Unite is clear that the closure of a third of the bank's branches will not only be concerning for staff but the local communities which will see their bank branch close," Unite said in a statement.

Clydesdale said the number of customers using branches for transactions have fallen by a third since 2011, while the number of people making digital transactions has increased.

Gavin Opperman, Clydesdale's customer banking director, said the changing use of technology means fewer staff and locations are needed.

"The changes announced today continue our journey towards a model that combines an enhanced digital platform with a right sized branch network," he said.

(Reporting By Andrew MacAskill, Editing by Lawrence White)