UN nuclear experts will visit Japan again next week to review government efforts to shut down the devastated Fukushima nuclear plant and prevent further worrying leaks, the IAEA said Tuesday.

"An IAEA expert team will visit Japan this month at the request of the Japanese government to review the efforts and plans to decommission TEPCO's Fukushima Daiichi nuclear power station," the International Atomic Energy Agency said in a statement.

The 19-strong mission will take place from November 25 to December 4, it said.

Tokyo has drawn up a long-term roadmap towards decommissioning the Fukushima plant, which saw the world's worst nuclear disaster in a generation when it went into meltdown after being hit by an earthquake and tsunami in March 2011.

"The IAEA mission will assess that plan and, in particular, efforts to manage contaminated water at the accident site and to remove fuel assemblies from the Spent Fuel Pool in Reactor Unit 4," the Vienna-based UN nuclear watchdog said.

Removing the fuel rods is a tricky operation but essential in decommissioning the complex, which is expected to take decades.

On Tuesday, the plant's operator TEPCO offered a first glimpse of the procedure, releasing video footage inside the reactor building where removal was under way.

Several teams of IAEA experts, including marine experts, have travelled to Japan in the past months amid reports that radioactive water from the plant was still seeping into the ocean.

During next week's visit, the IAEA experts will meet with officials in Tokyo and go to the Fukushima site