PERMANENT TSB faces the threat of an all-out strike after workers accused it of failing to guarantee their jobs will be safe when Irish Nationwide staff join the workforce.
In a memo seen by the Irish Independent the bank's unions have told members they have been left with "no option" but to hold a ballot for industrial action.
The Group of Unions, UNITE, SIPTU and Mandate, accused management of treating staff "with contempt" by refusing to rule out compulsory redundancies or explain the impact of the plan on workers.
Their message was sent to Permanent TSB's 1,800 workers yesterday after it emerged that it would take over Irish Nationwide's €3.6bn deposit book.
An auction of the state-owned bank's deposit books was held after Finance Minister Brian Lenihan asked the courts for permission to sell them.
The move means 240 Irish Nationwide staff will move to Permanent TSB.
In the memo, the Group of Unions said this showed that the bank knew in advance of its recent announcement of 360 voluntary redundancies that it would have to accept the transfer of Irish Nationwide employees if it secured its deposit book.
They said the Chief Executive of Permanent TSB, David Guinane, had assured Irish Nationwide staff that their terms and conditions would be honoured.
They said "no such assurances" were given to staff at Permanent TSB.
"Our members are rightfully incensed by the actions of Permanent TSB and will not take to being treated with contempt by their employer," they said.
"The Joint Union Group, having considered fully the unacceptable position the company has placed our members in, and their refusal to properly engage in meaningful negotiations in accordance with our agreements, have no option but to put in place the necessary arrangements to conduct a ballot for industrial action up to and including all-out strike.
"This decision was not taken lightly, but your union representatives feel that we have been forced into this action by the intransigence of Permanent TSB management."
They said a message from Mr Guinane to staff expressing his delight at acquiring the Nationwide deposit book showed "contempt for members".
"No reference or assurance has been given to our members as to the implication of Irish Nationwide staff transferring to Permanent TSB," the Joint Union Group said.