Many gambling web sites lack adequate safeguards and warnings to prevent children and teenagers from placing illegal bets, federal regulators said June 26.

In a survey of 100 popular internet gambling sites, the Federal Trade Commission found that one in five had no warnings for minors and most had disclaimers that were hard to find. The sites also lacked screening mechanisms to keep children out or had blocks that kids could get around easily.

“There is a growing problem with kids engaged in online gambling,” FTC Chairman Timothy Muris said at a news conference. He said minors gambling online may use their parents’ credit cards, costing them money and damaging their credit ratings.

In a warning to parents, the FTC added that online gambling can be addictive because “gambling in social isolation and using credit to gamble may be risk factors for developing gambling problems.”

The agency is investigating at the request of Rep. Frank Wolf, R-Va., who said the Bush administration is not doing enough to protect children from online gambling.

Muris said the FTC is continuing its research and plans to work with the online gambling industry to develop voluntary steps to protect children.

Gambling is illegal for minors in every state, but the majority of the gambling web sites surveyed were based outside the United States, the FTC said. The agency did not identify the sites.

Wolf said the number of internet gambling sites is climbing, and the industry probably will take in about $3 billion this year.

Sachin Jain was barely out of high school when he began four years of internet gambling.

He said he spent up to three hours each day gambling online on sports, placing bets for between $50 and $150. Before his parents made him stop and get counseling, he lost nearly $10,000.

“The attraction was you could bet on anything from soccer to golf to tennis,” said Jain, 22, a college student from Newark, Del. “It got out of control.”