WASHINGTON — Sex education programs that encourage teenagers to delay sexual activity but also teach them how to reduce their chances of getting pregnant or a sexually transmitted disease cut risky sexual behavior, increase condom use and lower the chances of getting the AIDS virus and other infections, an independent expert panel concluded in a report released Friday.

But there is insufficient evidence to know whether programs that focus on encouraging teens to remain sexually abstinent until marriage reduce the chances adolescents will engage in sexual behavior, be less likely to become pregnant or less likely to get a sexually transmitted disease, the panel concluded.

"There is sufficient evidence that comprehensive risk reduction efforts are effective," said Randy Elder, of the Centers for Disease Control and Prevention (CDC), who works with the Task Force on Community Preventive Services, an independent 15-member panel that issues public health recommendations.

"As regards abstinence education, after a similar look the task force determined that based on a number of problems with the studies presented to them there was insufficient evidence" to determine their effectiveness," Elder said.

The conclusions came after the task force reviewed an analysis of 83 studies of sexual education programs run between 1980 and 2007. The analysis was conducted by a 19-member team of experts assembled by the CDC to examine the politically sensitive question.

The findings come as Congress is considering whether to approve President Obama's request to discontinue setting aside funds specifically for abstinence programs but instead allocate funding based on whether scientific research supports the approach.

The findings were immediately welcomed by advocates of programs that reduce teen pregnancy and critics of abstinence programs.

"At long last, evidence and common sense have returned to public health policy," said James Wagoner, of Advocates for Youth, a Washington-based group. "The task force report endorses the comprehensive approach to prevention that includes condoms and birth control. We should be spending taxpayer dollars only on evidence-based programs."

"Most Americans would like their teens to stay away from sex," said Sarah Brown, of the National Campaign to Prevent Teen and Unplanned Pregnancy. "Strong research shows that the best way to do this, especially in schools, is to use a curriculum that encourages teens to delay sex and also — this is the key — talks to them about family planning and protection. This is actually what most adults think is the right message — delay and protect — kind of like trust but verify."