Hiroshima Mayor Kazumi Matsui and atomic bombing survivor and peace advocate Setsuko Thurlow urged Japan's new Prime Minister Fumio Kishida on Monday to take an active role in realizing a world free of nuclear weapons.

Matsui expressed hope that Kishida, who hails from a political family in Hiroshima, will take the initiative by making use of his experience as a foreign minister. The mayor urged the Japanese government to participate as an observer in a conference next year of the parties of the U.N. treaty to ban nuclear arms.

Japan -- the only country to have suffered atomic bombings, in Hiroshima and Nagasaki in 1945 -- has refused to join the treaty along with the world's nuclear weapons states as it relies on the U.S. nuclear umbrella.

"Kishida understands how the people of Hiroshima hope for peace without nuclear weapons, and he has experience and knowledge as foreign minister," Matsui said at a press conference.

Thurlow, a survivor of the U.S. atomic bombing of Hiroshima who has been campaigning to abolish nuclear weapons, said it is encouraging that Kishida was elected prime minister, as she called on Japan to join the U.N. nuclear treaty that took effect in January.

"If your comment is true about aiming to realize a world without nuclear weapons to be your life work, then please put that into action now," Thurlow said in a letter released by Japanese nongovernmental organization Peace Boat.

In a press conference on Monday, Kishida said he will consider what he can do to realize a "large goal" of eliminating nuclear weapons by communicating with U.S. President Joe Biden.

"As a prime minister who hails from Hiroshima, an atomic-bombed city, I will work toward a world without nuclear weapons," he said.

Thurlow, a Canada-based advocate, attended the Nobel Prize award ceremony in 2017 when the International Campaign to Abolish Nuclear Weapons, or ICAN, won that year's peace prize for its efforts to eliminate nuclear weapons.

"As a representative and citizen of Hiroshima, you have been outspoken in recognizing and deploring the catastrophic humanitarian impact of any use of nuclear weapons," Beatrice Fihn, the executive director of ICAN said in a separate letter.

"We look forward to your continued leadership to spread this message worldwide. A personal commitment, such as yours, is integral to universalizing a norm against nuclear weapons."