Japan's nuclear regulator on Wednesday approved a plan for the embattled operator of the disaster-hit Fukushima nuclear power plant to start freezing soil around its battered reactor buildings, in a move to reduce the massive amounts of radioactive water accumulating in the buildings.

The Nuclear Regulatory Authority approved the plan for the reactor buildings, crippled in the wake of an earthquake-triggered tsunami in 2011, with the work expected to be carried out by the plant's operator, Tokyo Electric Power Co on Thursday.

Freezing will start with the soil on the east side of the reactor buildings, which face the Pacific Ocean, as well as the majority of the west side.