WASHINGTON (AP) _ Cigarette smoking is on the rise among college students, jumping 28 percent in four years and causing health advocates to warn the nation may face more tobacco-caused disease.

``The rise in this group is really an alarming sign,'' said Henry Wechsler of Harvard University, whose study appears in Wednesday's Journal of the American Medical Association.

Wechsler's findings aren't a surprise _ smoking already had risen among teen-agers by 32 percent in the 1990s. So once those teens hit college, the rates among college students were sure to rise, too.

But the findings show that health officials must target college students to try to get them to quit, said Dr. Donald Sharp of the Centers for Disease Control and Prevention.

Until now, college students largely have been ignored by anti-tobacco programs. Historically, they were far less likely to smoke than less educated Americans, plus most smokers begin before they reach age 18. So health workers had focused more on persuading children never to try cigarettes and helping older smokers quit, Sharp said.

``Because of the highly addictive nature of nicotine, very few of those kids who became regular smokers in middle school and high school quit'' by college, he said. ``They will suffer a much higher rate of smoking-related illness and death as a result unless effective cessation can be provided to that group.''

Cigarette smoking is the leading preventable cause of disease and death. The government says it kills more than 400,000 Americans a year. Smoking causes a host of health problems, from lung cancer and heart disease to impotence.

Some 3,000 teen-agers begin smoking every day. The question is what was happening to people a little older _ the 18- to 24-year-olds now in college.

Wechsler compared surveys of over 14,000 students at 116 colleges in 1993 and again in 1997. Some 28.5 percent of college students smoked last year, up from 22.3 percent in 1993, he reported.

The vast majority started smoking in high school _ only 11 percent of college students had their first cigarette after age 18. But 28 percent moved from occasionally trying cigarettes in high school to becoming regular smokers in college, a finding the CDC called worrisome.

Half of college smokers reported they had tried to quit in the previous year, and 18 percent had made five or more attempts at kicking the addiction.

The findings stress the need for colleges to offer more smoke-free dormitories, because students might go without that cigarette if they can't smoke it conveniently, Wechsler said. He is about to study how smoke-free U.S. colleges are.