TOKYO - Japan and the United States plan to jointly build a spent nuclear fuel storage facility in Mongolia to serve customers of their nuclear plant exporters, pushing ahead despite Japan's prolonged nuclear crisis, the Mainichi daily said on Monday.

A Trade Ministry official said Japan, US and Mongolia officials, at a meeting shortly before Japan's March 11 earthquake, informally discussed possible construction of a nuclear waste storage facility for countries with nuclear power plants but no spent fuel storage capability of their own.

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He said there were no concrete plans at this time but the ministry would consider such a project if Mongolia were interested.

The Mainichi said the facility would allow Japanese and US nuclear plant exporters, which include joint ventures and units of General Electric , Hitachi and Toshiba, to better compete with Russian rivals that offer potential nuclear plant customers spent fuel disposal in a package.

Mongolia plans to have its first nuclear power plant by 2020 and to build nuclear fuel production capacity to tap its rich uranium resources, undeterred by the crisis at Japan's Fukushima nuclear power complex, a senior official at the state-owned MonAtom LLC said in April.

MonAtom represents the Mongolian government in mining and developing the country's uranium resources.

The trade ministry official denied the Mainichi's report that the three countries had originally planned to sign a deal on the spent fuel disposal project in February but it was postponed as Japan's Foreign Ministry opposed the schedule, citing a lack of consensus among Japanese ministries.

The Mainichi said a new date had not been set in the wake of the March 11 earthquake and tsunami in northeast Japan, which triggered cooling system malfunctions at Tokyo Electric Power Co's Fukushima Daiichi nuclear plant and led to radiation leaks into the atmosphere and the sea.

Engineers are still struggling to bring the plant under control.