Japan's Toshiba today filed its twice-delayed business results without an endorsement from its auditor, increasing the likelihood that the nuclear-to-TVs conglomerate will be delisted. 

The filing carried a disclaimer from auditor PricewaterhouseCoopers (PwC) Aarata that it was unable to form an opinion of the results. 

The move is unprecedented for a major Tokyo-based firm and puts the Tokyo Stock Exchange centre stage as it weighs the pros and cons of forcing Toshiba to delist. 

Failing to act tough with Toshiba would bring into question authorities' credibility in maintaining standards for investors.

But a delisting would complicate the crisis engulfing the firm, increasing financing costs and exposing it to further lawsuits from angry shareholders. 

Accountants have been questioning the numbers at US nuclear subsidiary Westinghouse Electric Co.

Massive cost overruns at four nuclear reactors under construction in the Southeastern US have forced its Japanese parent to estimate a $9 billion annual net loss and take drastic measures. 

PwC is questioning not only recent results but also probing the books at Westinghouse for the business year up to March 2016, sources have said. 

Toshiba has put up its prized memory chip unit and other assets for sale, Westinghouse has filed for Chapter 11 protection from creditors and may also be sold. 

The company also said today it was considering an initial public offering for smart meter group Landis+Gyr. 

Reuters last month reported that it was preparing a potential $2 billion divestment of the Swiss-based business. 

The decision on whether to delist Toshiba or not now rests with the bourse. 

Toshiba has been on its supervision list since mid-March after failing to clear up concerns about its internal controls a year and a half after a 2015 accounting scandal. 

There are no set rules governing how long the bourse should take to come to a conclusion. 

Separately, Taiwan's Foxconn has offered up to 3 trillion yen ($27 billion) for the chip business, nearly $10 billion higher than Toshiba's own estimate, the Wall Street Journal reported, citing people familiar with the matter. 

Such a proposal by Foxconn would also put Japanese regulators in a tough position as they have vowed to vet bidders to block a sale to investors it deems a risk to national security. 

Foxconn is considered such a risk because of its close ties to China. 

Japan's trade minister Hiroshige Seko repeated today that Toshiba's chip technology was important, not only for Japan's growth strategy, but also in terms of jobs and information security.

"For those reasons, we continue to carefully monitor Toshiba's business conditions and sale of its chip business," Seko said.