After a day of delays and confusion, Japan's Toshiba Corp said on Tuesday it would book a 6.3 billion US dollars hit to its US nuclear unit, a write-down that wipes out its shareholder equity and leaves the loss-making group scrambling for capital.

The company also said on Tuesday that its chairman, Shigenori Shiga, would resign, ending weeks of speculation.  Shiga, a former Westinghouse boss brought in to the top role last year after a 1.3 billion dollars accounting scandal in 2015 that shook up Toshiba's upper ranks. 

Hours earlier on Tuesday, the battered conglomerate rattled investors by failing to release its earnings on schedule, saying initially it was "not ready" and then announcing later it needed more time to probe its Westinghouse nuclear business after internal reports uncovered potential problems.

The figures eventually released were numbers that have yet to be approved by its auditor and Toshiba cautioned investors that a major revision was possible. Fully audited numbers are now not due till March 14 after the firm was granted a reprieve for its formal filing by Japanese regulators.

Shares in the group slid 8 percent, putting the company's market value at 973 billion yen (8.6 billion US dollars), less than half its value in mid-December. Just under a decade ago, the firm was worth almost 5 trillion yen.

Highlighting the scale of its financial concerns, Toshiba also ramped up plans to raise cash, announcing it would consider selling most, even all, of its stake in its prized flash-memory chips business, plus its troubled nuclear business Westinghouse.

(With inputs from Reuters)