The chairman of a U.N. conference on nuclear nonproliferation has sounded out member states on a plan to hold a gathering next summer following the postponement from the earlier scheduled January amid a surge in COVID-19 cases, diplomatic sources said Thursday.

The meeting to review the Treaty on the Non-Proliferation of Nuclear Weapons slated from Jan. 4 to 28 at the U.N. headquarters was put off again after being delayed three times from its original date in the spring of 2020 due to the coronavirus pandemic.

According to the sources, Gustavo Zlauvinen, who serves as chairman of the upcoming NPT review conference, presented two options for the meeting schedule -- Aug. 1 to 26 and Aug. 8 to Sept. 2 -- during consultations with member states on Thursday.

File photo taken in April, 2021 shows the United Nations headquarters in New York. (Kyodo) 

Some participants responded negatively, saying the dates are too late, the sources said, adding non-nuclear states want the next review conference to be held as a face-to-face session so they can have deeper discussions.

Zlauvinen, a former Argentine foreign minister, is expected to explore the possibility of hosting the gathering at an early date as well.

Even if the NPT review session is held next summer as proposed, it will mean a more than two-year delay from the regular quinquennial conference cycle, casting a cloud on progress in nuclear disarmament.

"It is very regrettable," said Kazumi Matsui, the mayor of Hiroshima, a Japanese city devastated by the world's first atomic bombing in 1945, referring to rescheduling of the conference.

"I was very disappointed as we were hoping the meeting would further solidify a movement to abolish nuclear weapons," said Tomihisa Taue, the mayor of Nagasaki, another Japanese city destroyed by a U.S. atomic bombing in World War II.

The NPT, joined by about 190 countries, is the world's most widely ratified nuclear arms control agreement. Its review conferences involving both nuclear and non-nuclear states, as well as survivors of the atomic bombings and civic groups, had been held every five years since 1975, with the last gathering in 2015.

The NPT requires the five permanent members of the U.N. Security Council -- Britain, China, France, Russia and the United States -- to commit to nuclear disarmament. Three other nuclear-weapon states -- India, Israel and Pakistan -- have not joined the pact.

North Korea, another nuclear-weapon state, pulled out of the treaty in 2003.

New York City, where the U.N. headquarters is located, is among the hardest-hit areas in another wave of coronavirus infections in the United States.

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U.N. nuclear nonproliferation gathering put off again due to COVID-19