Representatives of the states party to the Treaty on the Prohibition of Nuclear Weapons will hold their first meeting in Vienna in a bid to boost momentum for nuclear disarmament.

The three-day meeting opens on Tuesday, amid rising fears over Russia's possible use of nuclear weapons during its invasion of Ukraine.

The gathering will feature speeches by representatives of the participating parties.

Delegates are set to discuss a range of topics, including how to encourage nuclear-armed nations to participate in the treaty and to support victims of nuclear weapons and testing. They plan to release a document summarizing the outcome of their talks after they wrap up.

So far, 62 countries and territories have ratified the treaty, which entered into force in January of last year.

Nuclear powers like the US, Russia and China, as well as Japan, NATO members and other nations under a nuclear umbrella, are not party to the treaty. Among them, however, at least 29 nations including Germany, Belgium and the Netherlands are attending as observers, while Japan plans to sit out the meeting.

Ahead of the meeting, the Conference on the Humanitarian Impact of Nuclear Weapons took place at the same venue on Monday.

Kido Sueichi, who experienced the 1945 atomic bombing of Nagasaki when he was 5 years old, spoke at the conference. Kido said the nuclear arms ban treaty is what atomic bomb victims had hoped for, and that he hopes the treaty meeting will be successful.