Hitachi Zosen Corp., a Japanese builder of plants and bridges, is pursuing mergers and acquisitions as it seeks to strengthen its waste-to-energy plant business and expand to South Asia and the Middle East.

The Osaka-based company set aside ¥40 billion ($389 million) for M&A as part of a three-year business plan running to March 2017. As of yet, little of that allocation has been used, President Takashi Tanisho said.

"There are many companies we are looking at for M&A right now," he said in an interview in Tokyo on June 29. "Our focus is on the environment and green energy," he said, adding that waste-to-energy is an attractive M&A target.