TOKYO - Child pornography cases in Japan have surged almost 40% to a new record, police said Thursday, as the government looks to toughen rules against the sexual exploitation of minors.

Japan, a relatively low-crime society, is seen as a major global source of child porn. Although producing and distributing it is illegal, possession is not criminalised and online child porn has proliferated.

Newly released national police data for 2009 showed that child pornography has surged, especially on the Internet, in the form of still images and videos, with devastating consequences for the victims.

The National Police Agency said law enforcers took action in 935 child porn cases last year, up 38% from the previous year, to reach a new record since such data was first compiled in 2000.

A total of 411 children fell victim to pornographic exploitation, and 16 parents were arrested for using their children for pornography, police said.

In the most shocking cases, the victims were infants as young as one.

In one case, five people, including several mothers and a 46-year-old man, were arrested for allowing the man to sexually abuse girls aged between one and 12 and videotaping the scene.

In another case detailed by police, three mothers were arrested for selling porn photos of their daughters aged one to six.

The widespread availability of online child pornography in Japan is further fuelling the crime and traumatising many of the victims for the rest of their lives, experts say.

One woman has reported that she almost fainted when she found her nude pictures, taken years ago by her father, on the Internet.

"I was striking various poses cheerfully in tens of pictures, just like a girl model but stark naked or naked from the waist down," she said. "It was my father who took the photos.

"I felt angry when I looked at that seven-year-old girl that was me being photographed innocently and happily," she said in a letter posted on the website of the Japan Committee for UNICEF.

The problem has been much debated, but little action has been taken.

Now Japan's centre-left government, which took power last year, has launched a working team, made up of police, education, justice and other senior officials, to tighten measures against the crime.

The body is to draw up a series of new measures by June, which could include a crackdown on online child porn and the blocking of sites, public education campaigns, and steps to find and help the victims.

Law and gender issues expert Hiroshi Nakasatomi said Japan's current measures were "totally insufficient".

Nakasatomi said Japan was lenient on pornography, from red-light districts near residential areas to sexual magazine ads in trains and easy access to those magazines at convenience stores.

"What's special in Japan is the mass distribution and the low degree of segregation" of the porn industry, he said.

"Japan's law only targets producers and not the demand side. There are producers who do not mind breaking laws where there is demand," said the associate professor at Fukushima University based in northern Japan.

It is also important to oblige Internet service providers to block child porn sites as Britain, Italy and Sweden already do, he told AFP.

"Courts lack the recognition that making children adopt sexual poses constitutes abusive conduct," he said.

The heaviest penalty in child porn law is up to five years in prison.

For the victims, the damage can last a lifetime, said a university student on the UNICEF site, who reported she had been sexually abused and photographed by her uncle since she was five years old.

"I think I can't marry or have children as long as those pictures exist," she wrote. "I feel my life is over."