The president of Hitachi Ltd. (6501.TO) said Tuesday he is "very concerned" about possible further delays in the planned sale of the hard disk drive business to Western Digital Corp. (WDC) beyond March, as the U.S. company is still seeking regulatory approval from various international authorities.

"Authorities continue to examine the deal, and it's not clear what China will say," Hitachi President Hiroaki Nakanishi told reporters at company headquarters in Tokyo.

The Japanese electronics maker said in March it had agreed to sell its hard disk drive business to Western Digital for $4.3 billion, planning to complete the deal by the end of this year. But earlier this month Hitachi said it now expected the sale to be finalized by March 2012.

A delay beyond March would have a significant impact on Hitachi's earnings forecasts and cash flow for the current fiscal year, which currently factor in the expected effects of the sale.

Hitachi, one of Japan's biggest companies, had Y9.316 trillion in revenue in the last fiscal year ended in March. It has been restructuring by distancing itself from volatile businesses such as electronic devices and focusing more on technology services and infrastructure projects that target corporate and government clients rather than consumers.

-By Juro Osawa, Dow Jones Newswires; 813 6269 2794; juro.osawa@dowjones.com