The U.S. Postal Service's regulator has approved price increases amounting to 6% on most mail, news service reported.

A first-class stamp will cost 49 cents, up from 46 cents, starting Jan. 26. The increases of 4.3% approved Dec. 24 are on top of 1.7%, an amount equal to inflation, approved last month.

The Postal Regulatory Commission rejected a request to make the higher rates permanent, saying they will probably need to end in less than two years, Bloomberg News reported.

The increase is designed to boost revenue by $1.8 billion a year. The Postal Service lost $5 billion in the 2013 fiscal year ended Sept. 30.