Japan has asked Russia to send a liquid radioactive waste disposal facility for its troubled Fukushima plant, Russia's state-controlled nuclear corporation, Rosatom, said on Monday.

Currently workers at the plant are dumping water with low levels of contamination into the ocean to free up space to store highly radioactive water leaking from one of its damaged reactors.

Rosatom spokesman Sergei Novikov said talks were in progress and that the donation of the facility would be a "symbolic" act.

The floating waste-disposal facility, called Landysh (Lily of the Valley), designed for the disposal of waste from decommissioned nuclear-powered submarines, has been in use since 2001. Its construction, which cost around $35 million, was financed by Japan.

"We are ready to help our friends as they once helped us," Novikov said.

Tokyo Electric Power Co. (TEPCO), the Fukushima Daiichi plant operator, says around 11,500 tons of radioactive water will be released into the ocean. The water contains some 100 times the legal limit of radiation.

TEPCO has been using colored powder to trace the source of highly radioactive water leaking into the ocean near the plant, which was damaged by an earthquake and tsunami in mid-March.

The company says it is considering using silt-barriers in the ocean to prevent the further spread of radiation.