Apple Inc, Amazon.com Inc and Google have joined bidding for Toshiba's NAND flash memory unit, vying with others for the Japanese firm's prized semiconductor operation, the Yomiuri Shimbun daily reported on Saturday.

Toshiba shareholders on Thursday agreed to split off its NAND flash memory business, paving the way for a sale to raise at least $9 billion to cover U.S. nuclear unit charges that threaten the conglomerate's future.

The Yomiuri newspaper said bidding prices from Apple, Amazon or Google, owned by Alphabet Inc, were not known.

The Nikkei business daily reported on Friday that U.S. private equity firm Silver Lake Partners and U.S. chipmaker Broadcom Ltd have offered Toshiba about 2 trillion yen ($18 billion) for the unit.

About 10 potential bidders are interested in buying a stake in the microchip operation, a source with knowledge of the planned sale told Reuters earlier.

Suitors include Western Digital Corp, which operates a chip plant with Toshiba in Japan, Micron Technology Inc , South Korean chipmaker SK Hynix Inc and financial investors.

Toshiba officials were not immediately available for comment.