The Post Office may cut as many as 300 jobs as it closes or franchises 37 of its offices.
The Communication Workers Union said the job losses will include 127 financial specialist roles.
In a statement today the Post Office said it is seeking partners for 37 branches, in addition to 93 it previously announced.
“We’re committed to maintaining the Post Office’s special place on the high street and the changes we are making underpin our continued commitment to give communities in every part of the country access to essential services," said Roger Gale, the company's sales and trade marketing director.
“The Post Office’s network of more than 11,600 branches is easily the largest in the UK, with 17m customer visits a week. The vast majority of these branches are run with partners, and in the locations announced today we believe this will also be a more sustainable approach for the long term.
"With consumer habits changing, and the high cost of maintaining premises in prime high street locations, franchising helps us to keep services where our customers want and need them.
However, the Unite union accused the Post Office of "salami slicing a much respected an valued national institution in pursuit of profit".
"This is another nail in the coffin of the Post Office and a move to online will make the Crown Office network superfluous to requirements.
"Customers, who want to take up the services that the Post Office is offering, will have to do it online or on the phone."
Workers walked out on 19 December, with the strike running until Christmas eve.