Royal Mail is planning to increase the price of first class stamps by 3p.
The April hike - from 39p to 42p - would rake in more than £100 million a year, filling the huge hole in the firm's finances.
It would be the first time the price of stamps has risen by so much.
The plan is said to have been approved by industry regulator Postcomm. Royal Mail claims it would be unable to provide a doorstep service to every address in the land without the 7.7 per cent price rise.
It also wants to increase the cost of second class stamps by 2p, to 32p.
But Consumer Focus group chief Ed Mayo said: "This is paying for failure.
The only reason to hike up the price is because Royal Mail has failed to modernise as a business."
Royal Mail insisted last night: "No decision on price increases or decreases has been made yet."