Japan aims to get an agreement at this month's Group of 20 summit in Osaka on the reduction of plastic waste inflow to the ocean to zero by 2050, a source close to the matter said Saturday.

The government plans to raise the matter as a top agenda item when it hosts the two-day event from June 28 and hopes to assess progress in member countries' efforts in cutting such waste at a meeting of the U.N. Environment Assembly in 2021, the source said.

However, it remains unclear whether an agreement can be reached as the United States is expected to be cautious about such an initiative while European countries could call for a more ambitious goal, the source said.

Ahead of the summit, ways to strengthen the monitoring of plastic waste and promoting research, as well as providing financial and technological support to developing countries, will be discussed by G20 environment and energy ministers in Nagano Prefecture on June 15 and 16.

About 300 million tons of plastic waste is produced every year, of which 8 million tons end up in the ocean, significantly affecting marine ecosystems, according to the U.N. Environment Program.

Many countries are grappling with increasing amounts of plastic waste that degrades into small pieces when exposed to ultraviolet light and abrasion. Pieces measuring less than 5 millimeters in length are called microplastics.