TOKYO (Reuters) - U.S. hedge fund Elliott Management Corp raised its stake in Hitachi Kokusai Electric (>> Hitachi Kokusai Electric Inc) to just over 6 percent, a government filing showed, piling up pressure on KKR & Co LP (>> KKR & Co. L.P.) that has been trying to buy out the Japanese firm.

Elliott, a $33 billion (£24.42 billion) multi-strategy hedge fund with an aggressive activist shareholder arm, is known for buying stakes in companies that are in the middle of a takeover and forcing a better deal for shareholders.

Only last week, it said it had a more than 5 percent stake in Hitachi Kokusai. According to the latest filing, Elliott now owns 6.1 percent.

U.S. buyout firm KKR agreed in April to buy the chip-making equipment and video solutions business from Hitachi Ltd (>> Hitachi, Ltd.) in a deal valuing the unit at about $2.3 billion.

But the deal was put on hold last month after a third-party committee said the terms could be disadvantageous to minority shareholders.

Hitachi Kokusai shares closed at 2,974 yen on Tuesday, 18.8 percent higher than KKR's offer price of 2,503 yen ($22.42).

(This version of the story refiles to correct spelling of Elliott in headline)

(Reporting by Junko Fujita; Editing by Himani Sarkar)

Stocks treated in this article : KKR & Co. L.P., Hitachi, Ltd., Hitachi Kokusai Electric Inc