It’s not the first thing that comes to mind when it comes to online shopping.

But someone in Japan apparently tried to sell uranium that was found to be radioactive when authorities tested it, and Japanese police want to get to the bottom of how they obtained it.

The seller, whom Tokyo police were able to track down, offered the substance on Yahoo’s online auction with the title “Uranium 99.0 percent.”

An initial test of the powder, which was in a glass tube, indicated it was radioactive, according to BBC News.

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National laws forbid the handling of radioactive substances except in cases where people have authorization.

Several people placed bids, the Japan Times said. Police have brought them in for questioning, it added.

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The seller said he bought the uranium from an online seller outside Japan.

When Yahoo was notified about the sale, it stopped the auction, the BBC said.

Authorities have asked the Japan Atomic Energy Agency to check on what type of uranium it is – depleted or concentrate.

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The advertisement ran on the auction site in 2017.

Violators of the law could face a year in jail and a fine of roughly $9,000.

When found in its natural state, uranium has only 0.7 percent of the 235 isotope. To be used for nuclear power or weapons, uranium must be concentrated.