U.N. Secretary General Antonio Guterres on Tuesday urged leaders attending the upcoming Group of Seven summit to commit to a nuclear weapon no-use policy and voiced his concern about the possible weaponization of artificial intelligence.

Speaking to a group of reporters at the U.N. Headquarters in New York, Guterres said "it's time" for nuclear weapons states to declare they will not use the armaments "in any circumstance."

U.N. Secretary General Antonio Guterres speaks to Japanese media organizations at the U.N. headquarters in New York on May 16, 2023. The world body said the same day he will visit Hiroshima to attend events related to the upcoming Group of Seven summit in the western Japan city. (Kyodo) ==Kyodo

"This is the moment in which we must insist on the need of revitalizing disarmament, and especially nuclear disarmament," Guterres told reporters from Japanese media outlets including Kyodo News ahead of his trip to Hiroshima, which is preparing to host the G-7 summit.

Japan, as the only country to have been attacked by nuclear weapons, is a "particular moral authority" on the subject, he said.

The leaders of the G-7 industrial states -- Britain, Canada, France, Germany, Italy, Japan and the United States plus the European Union -- are set to begin their three-day meeting on Friday.

Japanese Prime Minister Fumio Kishida, who represents a district in Hiroshima, one of two cities devastated by a nuclear weapon in the closing stages of World War II in 1945, has said he seeks a "world free of nuclear weapons."

At the G-7 summit, Guterres is expected to take part in working sessions on climate change and the reform of global financial systems. He is also expected to meet with Kishida on the sidelines of the event.

Guterres visited Hiroshima as U.N. secretary general for the first time in August 2022, when he commemorated the 77th anniversary of the first atomic bomb attack.

Guterres recalled that on his past visits to the city, he was impressed by the "courage (and) the resilience of the hibakusha," referring to the survivors of the atomic bombings of Hiroshima and Nagasaki.

Eight invitee nations -- Australia, Brazil, Comoros, the Cook Islands, India, Indonesia, South Korea and Vietnam -- are also expected to participate in the summit.

Recent developments in the field of artificial intelligence are also expected to be brought up at the summit.

The U.N. chief voiced his concern about the possible weaponization of artificial intelligence, expressing unease specifically about their use in arms systems.

"The idea that we will have, one day, arms systems without any human agency is totally unacceptable," he said.

He said that even though artificial intelligence "will not be easy to regulate," countries should agree to define red lines in their development. "Even the entrepreneurs that are in the frontline of the developments of A.I. recognize that we need to put some order in the system."

On the Russian invasion of Ukraine, Guterres expressed his doubts about the possibility of "fruitful" peace negotiations at present, adding the fallout from the war is being felt around the world, especially in the price of food.

On a U.N.-brokered deal also involving Russia and Turkey that enables Ukraine to export grain through the Black Sea, Guterres said he expected the agreement to be renewed before it expires Thursday.

Russia has threatened not to extend the agreement over issues concerning its export of food and fertilizers.