Telephone chat lines operated by TOT Plc, which are popular with thousands of teenagers to set up dates, are responsible for about 10 cases of underage girls being drawn into illicit sex and being abused, a youth advocacy group alleges.

The Mirror Foundation's information centre for missing people said yesterday it had investigated the cases and found that the girls had been using the phone chat lines at the time.

The foundation's Worrachet Kheowjan said a 14-year-old girl named Ae had gone missing from home and police found she had made lengthy telephone calls to the 1900 chat lines run by TOT.

Her parents had complained that their phone bill was several thousand baht each month and their TOT statement showed a series of 1900-xxx-xxx chat line numbers.

Ae's friends told the police she often spoke with strangers on the chat lines. She eventually agreed to a date with a man and then went missing. Police later found her hanging around with a group of teenagers and took her home.

Ae has now stopped studying and dropped out of junior high school. She still uses the chat line services and sporadically goes missing from home.

Worrachet said another 14-year-old, Bee, went missing from home after spending long periods in the chat lines, running up a mobile-phone bill of Bt3,000 a month. Police contacted several males who had been chatting with Bee and they admitted that they had had sex with her.

Two weeks after she went missing, Bee returned home and her parents took her to a psychiatrist. Today she still uses the chat lines.

The foundation recently petitioned the National Telecommunications Commission  and the Culture Ministry to regulate the chat lines more strictly.

Chief of the ministry's Watchdog Centre, Ladda Thangsupachai, said advertisements for the chat services, using the 1900-xxx-xxx numbers were found in all media, especially general magazines. The use of suggestive or inappropriate images in the adverts could attract teenagers to the service, she said.

"The state authority which has given out the concession should strictly control the service," Ladda said.