WASHINGTON — The U.S. Postal Service on Thursday proposed slight increases for mailing postcards and international letters — but wants to leave first-class “Forever” stamps at their present 49 cents.

Under a filing with the Postal Regulatory Commission, letters to international destinations would rise from $1.15 to $1.20. Postcards would rise from 34 cents to 35 cents.

The increases being proposed would become effective April 26, if the requests are granted.

On first-class mail, every ounce over 1 ounce would cost an additional 22 cents, up from 21 cents. And letters to all international destinations would go from $1.15 to $1.20.

The filing does not affect Postal Service shipping products and services.

The Postal Service said the requested price increases are the latest in a series of steps “to achieve financial stability.”

“By growing volume, revenue and contribution, the Postal Service will continue to meet America’s mailing and shipping needs well into the future,” the agency said in a statement. Letters to international destinations would rise from $1.15 to $1.20. Postcards would rise from 34 cents to 35 cents. “While improving efficiency in streamlining its network and seeking legislative changes, the Postal Service must address an outdated business model,” it added.

The Postal Service receives no tax dollars for operating expenses. It relies on the sale of postage, products and services to raise the revenues needed to pay for its operations.

Before they take effect, the new rates must be approved by the commission.

The last increase in first-class postage was a 3-cent boost to 49 cents that took place Jan. 26, 2014.

Forever stamps bought now are good for first-class postage up to 1 ounce regardless of future rates.