The capability of the finance sector to recover from the recession has been hit by the scale of the job losses in the industry, according to report.
Around 20,000 jobs have been axed by finance firms since the start of the year.
That has "seriously" damaged their chances of getting back on their feet, according to the Unite.
The union warned that continued job losses would only make the situation worse.
National officer Rob MacGregor said: "Unite is infuriated that banks and insurance companies are failing to recognise the damage that will be done to their businesses if they continue to simply slash thousands of staff each month.
"Nearly 20,000 job losses in the last four months represents a significant loss in the sector.
"The financial services industry must ensure that it protects its workforce in order to stand a chance of emerging from the current crisis.
He added: "Without these highly trained and experienced people there is no chance that the UK will be able to re-build its reputation for a world class industry.
"The union wants to see companies in the financial industry consider the long-term implications of their short-term cost-saving plans."
Unite said its members worked in processing centres, bank branches and insurance offices and were not the highly paid executives and traders that caused the economic meltdown.