GENEVA, May 14 -- An estimated 1.3 million adolescents died in 2012 worldwide, which mainly caused by road traffic injuries, HIV/AIDS, and suicide, said the World Health Organization (WHO) on Wednesday.

The report, titled "Health for the world's adolescents" and released by WHO, pointed out that the road traffic injuries are the number one cause of adolescent deaths globally, followed by cause of illness and disability.

It noted that the increasing access to reliable and safe public transport, road safety regulations and the establishment of safe pedestrian areas around schools could reduce road risks among adolescents.

Meanwhile, the report stressed that the mental health problems take a big toll. For instance, depression dominates the top cause of illness and disability in this age group, and suicide ranks number three among causes of death.

It reminded that if adolescents with mental health problems get the care they need, deaths and suffering throughout life could be prevented.

"We hope this report will focus high-level attention on the health needs of 10 to 19-year-olds and serve as a springboard for accelerated action on adolescent health," Flavia Bustreo, assistant director-general of WHO said in a statement.

Furthermore, the report estimated the number of HIV-related deaths among adolescents is rising. HIV now ranks as the second cause of deaths in adolescents globally.

Thanks to childhood vaccination, adolescent deaths and disability from measles have reduced by 90 percent in the African region between 2000 and 2012. However, common infectious diseases that have been a focus for action in young children are still killing adolescents.