Toshiba's CEO resigned on Tuesday, the Japanese conglomerate said, adding fresh uncertainty after already revising plans to split its businesses and just weeks before a key shareholder vote.

Satoshi Tsunakawa had been chief executive for less than a year at the tech and industrial giant, which has lurched from crisis to crisis in recent decades.

It comes ahead of an extraordinary shareholder vote on March 24 on Toshiba's plan to spin off its devices unit and sell "non-core" business including Toshiba Tec.

The proposal is a revision of an earlier one to split into three companies, which got a mixed response, but Tsunakawa's resignation could spark another rethink on the plans.

Toshiba said its new CEO Taro Shimada would "lead the company that will run the energy and infrastructure business" after the electronic devices segment is spun off in a binding resolution to be voted on in 2023.

Tsunakawa will continue to serve as interim chair of the board of directors, Toshiba said in a statement.

The sprawling conglomerate dates back to 1875 and was once a symbol of Japan's advanced technological and economic power, but it has been mired in turmoil in recent years.

Having staged a recovery after a series of scandals and financial problems in the 2010s, it returned to the first section of the Tokyo Stock Exchange last year.

But a takeover offer from private equity fund CVC Capital Partners stirred tumult within the firm around allegations it was intended to blunt the influence of activist investors.

Tsunakawa's predecessor Nobuaki Kurumatani, who previously worked for CVC, resigned as CEO in April 2021, insisting his decision was not related to the buyout controversy.

Then in June, Toshiba shareholders voted to oust the board's chairman after an inquiry found that the company "devised a plan to effectively prevent shareholders from exercising their shareholder proposal rights and voting rights" at a meeting the previous year.

Japan confirms cyberattack hit Toyota supplier

Japan's government said Tuesday that a cyberattack was behind disruption at a Toyota supplier that forced the top-selling automaker to halt operations at domestic plants for a day.

Local media reported the attack on parts supplier Kojima Industries was a possible ransomware attack, with the firm saying it detected a "threat message" on Saturday night before discovering its server was "infected with a virus".

Its statement had to be forwarded by Toyota as Kojima's server is still down.

The parts maker still does not know when it will be able to restore its system and resume production, a Kojima spokesman told AFP.

Japan's top government spokesman Hirokazu Matsuno confirmed "a cyberattack" on the company, but declined to offer details, saying it was still being investigated.

He also warned that the "risk of cyberattacks is rising due to the current situation, including Ukraine," calling for companies to "strengthen cyber security measures."

The leading business daily Nikkei reported the cyberattack involved ransomware, a kind of malware that effectively ransoms a victim's information. 

Toyota said Monday the system failure at Kojima Industries forced it to suspend operations at the 28 lines of its 14 domestic plants on Tuesday.

But it confirmed on Tuesday that it would resume operations the next day.

The cyberattack comes with nations that have imposed sanctions on Russia over its Ukraine invasion, including Japan, on high alert over possible retaliatory cyberattacks.