Warren Buffett's Berkshire Hathaway raised its holdings in five Japanese trading houses, regulatory filings showed on Monday, in the U.S. conglomerate's latest investments in Japan's top commodity firms that began nearly five years ago.

Warren Buffett has indicated that the trading houses have agreed to 'moderately' relax a previous ceiling of 10% on his stakes, leaving room for further buying.

Berkshire Hathaway raised its holdings in five Japanese trading houses — Itochu, Marubeni, Mitsubishi, Mitsui and Sumitomo.