Eight people were found dead on Wednesday in what police in South Korea said were two separate group suicides, a report said. Five youths -- four women and a man -- breathed in toxic fumes after burning coal briquettes inside a vehicle which had its windows sealed with dark plastic sheets just south of Seoul.
They left suicide notes in their pockets, police said.
In the second incident, three young men were found dead in a motel room to the east of the capital, Yonhap news agency quoted police as saying. The report said officers believed this group had also used coal briquettes.
The eight deaths sparked concerns that Internet-based suicide pacts might be on the increase again in South Korea, which has the world's third highest suicide rate.
Suicide is the leading cause of death among young people in South Korea, with heavy stress from its highly competitive education environment and job market taking a lethal toll.
In April last year, South Korean police arrested an Internet website operator in a probe into a series of Internet-based group suicides that left at least 14 people dead in the space of three weeks.
The health ministry says 23.9 in every 100,000 South Koreans committed suicide in 2007, the highest rate among members of the Organisation for Economic Cooperation and Development group of developed countries.