Unite, a union that represents 200 AIB workers, has threatened to launch industrial action against the state-owned bank.
The union accused AIB of failing to honour a pensions agreement made by AIB-subsidiary EBS with its employees.
"The company has consistently refused to engage with Unite, not only in respect of our members' pension scheme but also in respect of individual workers," Unite regional officer Colm Quinlan said.
The bank said it "always adopts a partnership approach when dealing with issues that affect our employees" in response to the Unite statement.
"In this instance, AIB is open to having a meeting with Unite representatives to clarify any issues relating to the EBS pension scheme," it said.