The four released a statement following an explosive shareholder-commissioned investigation that accused Toshiba and the government of colluding to pressure foreign investors.

"The report made clear that certain members of the management and board took actions that were unacceptable and directly against the interests of our shareholders," the four said in their statement.

"We are no longer in support of the full slate of director candidates which were nominated by Toshiba for the upcoming AGM," they said.  

(Reporting by Makiko Yamazaki; Editing by David Dolan)