TOKYO (Reuters) - Japan's Toshiba Corp <6502.T> said it has asked regulators to allow it to delay the release of its earnings, including a writedown on its U.S. nuclear business, by a month while it probes internal controls at its Westinghouse unit.

Toshiba said in a statement it needs to look at allegations that Westinghouse's management exerted inappropriate pressure over the calculation of assets and liabilities for the nuclear construction company it bought from Chicago Bridge & Iron <CBI.N>.

Toshiba was due to announce quarterly earnings on Tuesday but now says it wants an extension, which if approved would extend the deadline to March 14.

(Reporting by Makiko Yamazaki; Editing by Edwina Gibbs)