Toyota Motor Corp. announced Tuesday it has agreed to a tieup with Isuzu Motor Lt. that will include acquiring a 5.9 percent stake in the truck maker.

Toyota will spend 44 billion yen to buy 40 million shares from Mitsubishi Corp. and 60 million from Itochu Corp. It said that forming a capital alliance with Isuzu will ensure a smooth business collaboration. The deal will make the world's No. 2 automaker the third-largest shareholder in Isuzu after Mitsubishi and Itochu.

Toyota and Isuzu will set up a joint group later this month to discuss how they can collaborate on research and development of diesel engines and other environmental technologies. The collaboration could include the truck maker sharing its diesel engines with Toyota and the carmaker supplying its hybrid technology to Isuzu, the automakers said.

"Global demand for diesel engines is expected to rise in the future," as a way to protect the environment, Toyota President Katsuaki Watanabe said during a joint news conference in Tokyo with Isuzu President Yoshinori Ida.

"Although we have our own diesel technology, Isuzu has high technical skills in diesel engines," Watanabe said.