Hitachi Ltd, Japan's biggest electronics firm by revenue, plans to raise up to 400 billion yen ($4.5 billion) through a public share offering and an issue of convertible bonds to shore up its capital, two sources familiar with the matter said.

The sources, who asked not to be named as the matter has not been made public, said that Hitachi plans to raise 300 billion yen through a public share issue and 100 billion yen through convertible bonds.

The share issue would boost the number of Hitachi's shares outstanding by 30 percent.

(Reporting by Reiji Murai and Kentaro Hamada; Editing by Keiron Henderson)