A major investor in Toshiba Corp. has called for a third-party investigation into the conglomerate's annual shareholders meeting, saying its vote was not fully recognized in a potential breach of governance.

The demand from Singapore-based 3D Investment Partners is likely to sharpen scrutiny of the treatment of Toshiba's foreign investors. It follows a contentious, but failed, attempt by foreign shareholders to elect some new independent directors to Toshiba's board at the July 31 meeting.

3D said voting rights representing a 1.1 percent stake in Toshiba were not reflected in the results of the meeting, according to an Aug. 9 letter from the hedge fund to Toshiba's outside directors seen by Reuters.