GENEVA -- A senior official with the Universal Postal Union (UPU) said Thursday that the decision of the United States to withdraw from the UPU treaties was a serious one, but they can "resolve the matter amicably".

UPU deputy director general Pascal Clivaz said in a statement that they would continue to seek a constructive dialogue and to try to resolve the situation, while upholding the UPU Constitution.

According to Clivaz, the UPU, an international body of the United Nations (UN), received a letter from the US Secretary of State Wednesday afternoon, which said the withdrawal "shall be effective one year after the day on which you receive this notice".

"The United States of America is among the founding members of the UPU and has over the years made a tremendous, positive contribution to the Union. It is, therefore, regrettable that the US has taken this step," the UPU official noted.

He added that the UPU director general Bishar A. Hussein would seek to meet with US government representatives to further discuss the matter.

"I remain hopeful that, through discussion, through a constructive dialogue, we can help to resolve this issue to everyone's satisfaction," he said.

Founded in 1874, the Universal Postal Union is a United Nations (UN) agency headquartered in the Swiss capital of Bern. It is one of the world's oldest international organizations and is the primary forum for cooperation between postal sector players.

"This will begin a one-year withdrawal process, as set forth in the UPU Constitution," the White House said Wednesday, adding the Department of State will seek to "negotiate bilateral and multilateral agreements" that resolve the problems related to reform the terms of the postal treaty.

"If negotiations are successful, the Administration is prepared to rescind the notice of withdrawal and remain in the UPU," said the White House.

The UPU, which consists of 192 members and is located in Switzerland, sets shipping rates for international mail in a way that guarantees lower prices for shipments from developing economies and higher rates for those from advanced economies.

The Donald Trump administration believed that the current structure of international mailing rates benefit some developing economies, while putting American small businesses and manufacturers at a severe competitive disadvantage.

The move against the UPU represented another U.S. departure from multinational organizations and treaties, after it pulled out of the Paris climate accord, the UN Global Compact on Migration, the UN culture and education body UNESCO, the UN Human Rights Council, as well as the Iran nuclear deal.