The Post Office is cutting 300 jobs due to the closure and franchising of Crown offices – Sky News reports.
127 specialist financial roles are also being cut.
The Communication Workers' Union (CWU) said these cuts add to the 2,000 from last year.
Dave Ward, CWU’s General Secretary, said: “The latest round of closures is further evidence that the Post Office is in crisis and that the Board of the company, backed by the Government, is simply pursuing a strategy of slash and burn.
“Today's announcement comes less than three weeks after the closure of a major Government consultation on the future of the Post Office and sticks two fingers up to everyone who took part in this.
“While the Government spent yesterday talking about building a shared society, today's announcement pressing on with the destruction of yet another public service shows we are reaching the point where we will have little left to share.
“The CWU will not accept this and we will be stepping up our political and industrial campaign to fight for the future of the Post Office.”
The views of the public, who sent 75,000 postcards to the Government asking for an end to the closure and franchise programme, “have been completely ignored”, he claimed.
Roger Gale, Post Office’s Sales and Trade Marketing Director, said: “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.
“Post Office has a strong record of supporting people through change and we will be keeping affected staff fully informed as we develop our plans.”