Japanese police say more than 900 people under the age of 18 were victimized through social media in the first 6 months of this year.

The National Police Agency says the number of reported cases stood at 919, up 30 from last year. The number is a record high for the January-to-June period since recordkeeping began 9 years ago.

Of the cases, 289 involved pornography, 243 adults paying youths for sexual services, and 350 other forms of commercial exploitation.

Victims aged 15 to 17 accounted for 70 percent of the total. The youngest was 9.

Twitter was involved in more than a third of the cases.

A recent legal revision obliges phone sellers to set up filtering on phones sold to people under 18 so that access to harmful sites can be blocked.

Police say about 90 percent of the victims were not using the filtering function.