Toshiba Chief Executive Officer Satoshi Tsunakawa said he will do all he can to ensure the company doesn't fall into negative net worth as a result of a writedown on its U.S. nuclear unit.

The conglomerate will review its overseas nuclear business, Tsunakawa said, but added it has no plans to sell its infrastructure business.

Toshiba's board on Friday approved plans to make its core memory chip business a separate company and seek outside investment in it.

(Reporting by Makiko Yamazaki; Editing by Edwina Gibbs)