Japan's release of treated radioactive water from the crippled Fukushima No. 1 nuclear plant into the sea is "progressing as planned and without any technical concerns," the U.N. nuclear watchdog has said.

The International Atomic Energy Agency wrapped up its safety review Friday, two months after the discharge began at the northeastern Japan complex devastated by a massive earthquake and tsunami in 2011. It plans to compile a report on its latest four-day mission by year-end.

The IAEA safety review "will continue to proceed in an independent, objective, science-based and transparent manner, during the discharge and after," it said on its website.

Seven IAEA officials and experts from nine of the 11 task force member countries, including China and Russia — which have criticized the release and imposed import bans on Japanese seafood — took part in the review mission, which involved an on-site inspection of the water treatment and discharge facilities at the nuclear complex.

During their stay, the members of the mission also exchanged opinions with officials of the Japanese government, plant operator Tokyo Electric Power Company Holdings Inc. and the Nuclear Regulation Authority over the operation of the discharge facility at the plant and environmental monitoring procedures.

Since August, the plant operator has ejected about 15,600 tons of water treated with a liquid processing system that removes most radionuclides except tritium. The tritium is diluted with seawater, leaving it with a concentration level one-fortieth of that permitted under Japanese safety standards, before it is discharged.