Japanese police took action against over 300 child pornography cases in the first half of 2008, up 17 percent from the same period last year, police said, a sign both awareness and Internet sexual exploitation are rising.

The report comes as some lawmakers are discussing a ban on the possession of child pornography in Japan, where only production and distribution, and not possession, of obscene images of people under 18 are illegal.

The number of legal actions in the first half of 2008 tripled from the same period in 2004, according to data from the National Police Agency. Almost 40 percent of the cases involved the Internet.

"We are strengthening the crackdown on child porn as society becames more aware of the issue, and child porn is getting rapidly copied and spread on the Internet," said Takafumi Ozawa of the National Police Agency.

"It's difficult to say how widespread child porn is. This is probably only a small part of what's out there," he added.

Japan and Russia are the only two countries among the Group of Eight rich nations not to have banned possession of child pornography.

Critics including Washington's ambassador to Tokyo say Japan's failure to ban possession has hampered international investigations into child porn rings.

In June, a bill to ban possession of child porn was submitted to parliament's lower house. It is set to be debated in a parliament session expected to start in September.