The Unite trade union said that it will fight for guarantees of no compulsory redundancies following Lloyds Banking Group's announcement earlier today that it is to close its Warrington telephone banking centre and cut 645 jobs.
Lloyds has already cut more than 2,400 jobs in this year, leading to 'plummeting' staff morale, says Unite.
The bailed out bank plans to close the call centre as "telephone banking call volumes are falling as digital usage continues to grow", it said in a statement.
Around half of the 645 job cuts will come from the telephone centre closure, while the majority of the rest will come from Lloyds' wealth business and HR function.
The Lloyds statement said: "As part of the group's simplification programme set out in its 2011 strategic plan, we have reached the decision to close Warrington Contact Centre, leading to around 180 role reductions, with around 120 roles also moving to nearby Speke, in Liverpool.
"Telephone banking call volumes are falling as digital banking usage continues to grow, and we are refocusing the business to reflect these changes in our customers' habits, while ensuring we maintain our high standards for those who wish to continue using our telephone banking systems by bringing our telephone banking colleagues together at fewer, more specialised sites."
After the announcement, Britain's largest union hit out at the bank with Unite national officer Rob MacGregor saying: "The closure of the Warrington centre will hit the local economy and risks damaging customer service.
"Lloyds' staff have worked hard since it was bailed out by the taxpayer to make the bank a success. Their reward has been continual uncertainty and attacks on their pensions.
"Lloyds needs to give its workforce stability and guarantees of no compulsory redundancies. Only then will the bank be able to live up to its motto to 'Make Britain Prosper'."