The International Atomic Energy Agency on Monday started a fresh probe into Japan's Fukushima nuclear plant, where leaks and powercuts have dented public confidence in clean-up efforts.

A 12-strong IAEA mission held a meeting with officials from the Japanese government and operator Tokyo Electric Power Co (TEPCO) in Tokyo ahead of their on-site inspection at the plant from Wednesday to Friday.

The eight-day trip by the nuclear experts and international specialists was at the request of the Japanese government and is the third of its kind since the plant was knocked out by a tsunami in March 2011.

"After this week of discussions, I hope that we will have new information to give our assessment and to give our feedback to the government of Japan," Juan Carlos Lentijo, head of the mission, told reporters.

The IAEA team is scheduled to submit a report to the government and TEPCO on April 22, officials said.

The mission came as workers at the troubled plant battle with a series of radioactive water leaks, the latest in an increasingly long line of problems.

Two years since the worst nuclear accident in a generation, the plant remains fragile, with systems to cool spent nuclear fuel failing repeatedly in a matter of weeks in March and April.

The IAEA team is mainly focusing on the decommissioning process but will look into TEPCO's measures to solve leakages and blackouts that caused cooling system failures, government officials said.

The plant was hit by a 9.0-magnitude earthquake and massive tsunami on March 11, 2011, prompting reactor meltdowns that forced tens of thousands of people to flee their homes.

Many remain displaced and some will never be able to return.