Supposedly final talks in South Korea in 2024 towards an agreement failed, and a renewed effort in Geneva last August likewise collapsed in overtime.

A Japanese environment ministry official said that the "informal" closed-door meeting among "working-level officials" through Tuesday was not expected to result in any official announcement.

"Japan is in a position of pushing for progress on the issue, and so is hosting the meeting," the official told AFP without wishing to be named.

She added that "little progress" has been made since August, other than the election in early February of Chile's chief climate negotiator Julio Cordano as chairman.

"Plastic pollution is a planetary problem that affects everyone: every country, every community and every individual," Cordano warned after being elected.

"If we don't take concerted action, it will get much worse in the coming decades. A treaty is urgently needed," he said.

More than 400 million tonnes of plastic are produced globally each year, with half for single-use items.

A large bloc of states wants bold action such as curbing plastic production, while a smaller clutch of oil-producing states wants to focus more narrowly on waste management.

Countries expected to be present in Tokyo include big oil producers like Saudi Arabia, Russia and the United States as well as islands states Antigua and Barbuda and Palau, plus China, India and the European Union.

The UN's environment chief told AFP in an interview in October that a global treaty remains "totally doable".

"No-one has walked away and said, 'this is just too hopeless, we're giving up'," United Nations Environment Programme (UNEP) executive director Inger Andersen said.