There is a proposal to merge the two banks and create the country's second largest commercial bank after the State Bank of India.
All India Bank Officers' Confederation has drawn up agitation plans since the merger of any public sector bank would render officer staff surplus. It would also lead to the closure of overlapping branches.
If BoI and UBI were merged, this would render nearly 25 per cent of officers surplus, AIBOC general secretary Shantha Raju told the media on Friday.
Citing the example of Karnataka, which is known to have a vast banking presence, Raju said any merger would result in a closure of up to 40 per cent of the branches of the merged entity.
As all the 27 public sector banks have different work cultures, AIBOC wants that the government maintain the independent character of each bank.
Meanwhile, the confederation will also oppose any move by the government to dilute its shareholding below 51 per cent.