A Japanese man was sentenced to death for killing three people he met through an Internet site for group suicides in 2005, a local court spokeswoman said.

The unemployed man, Hiroshi Maeue, 38, invited a 14-year-old boy out to commit suicide together using charcoal fumes, but then suffocated him to death, Kyodo news agency said.

Maeue, killed two others ? a 25-year-old woman and a 21-year-old male college student ? by similar means and abandoned their bodies, Kyodo said.

The nature of the crimes was cruel and made Maeue difficult to correct, Presiding Judge Kazuo Mizushima of the Osaka District Court in western Japan was quoted saying in handing down the sentence.

Maeue?s defense counsel appealed the ruling, Kyodo added. An increasing number of suicide Web sites have cropped up in recent years in Japan, where the suicide rate is one of the highest among industrialized countries.