The mayors of Nagasaki and Hiroshima have been invited to the ceremony where an international group that has campaigned for a treaty banning nuclear weapons will be awarded the Nobel Peace Prize, the cities said Wednesday.

Hiroshima Mayor Kazumi Matsui is expected to attend the ceremony to be held on Dec. 10 in Oslo, while Nagasaki Mayor Tomihisa Taue is considering attending, city officials said. They would be the first Hiroshima and Nagasaki mayors to attend a Nobel Peace Prize ceremony.

The efforts of 2017 Nobel Peace Prize winner, the International Campaign to Abolish Nuclear Weapons, led to the adoption in July of a landmark U.N. treaty outlawing nuclear weapons. ICAN is seeking the attendance of atomic bomb survivors who have thrown their support behind the treaty.

Although the Japanese government has not joined the treaty, likely due to its reliance on the protection of the U.S. nuclear arsenal, the mayors of Hiroshima and Nagasaki have backed efforts for a treaty to prohibit nuclear weapons.

Speaking at a U.N. conference to negotiate a nuclear weapons ban treaty in June New York in June, Matsui said the "earnest wish" of the atomic bomb survivors, known in Japan as hibakusha, is to "witness the prohibition of nuclear weapons in their lifetime."

Taue, meanwhile, attended the signing ceremony of the new treaty in New York in September.

Japan is the only country to have suffered atomic bomb attacks, with the United States dropping the first on Hiroshima on Aug. 6, 1945, and the second on Nagasaki three days later, during the final stages of World War II.

Around 210,000 people are estimated to have died from the attacks by the end of 1945 and many survivors were left suffering from health problems in the following years.