Japan's nuclear regulator has issued a rare warning to the science minister, telling him to disqualify the operator of a plutonium-burning reactor plagued with poor safety records.

The Nuclear Regulation Authority says the government-run Japan Atomic Energy Agency must be replaced within six months or the ministry will have to consider shutting down the Monju plant.

The 1 trillion yen ($8.2 billion) plant has not produced power for 20 years since the Dec. 1995 accident that occurred months after it went online.

The authority told Science Minister Hiroshi Hase that the atomic agency is not qualified to safely operate the complex reactor.

Monju is designed to burn plutonium and produce more of it while generating electricity. Japan's stockpiling of plutonium reprocessed elsewhere has raised concern about nuclear proliferation.