WASHINGTON (AP) _ A consumer group asked the government Monday to ban the nation's first zero-calorie fat replacer, which the group says gave 192 Midwesterners diarrhea, some who were sick for days.

Citing an 11-year-old Colorado boy who missed three days of school after eating six ounces of Frito-Lay potato chips made with olestra, the Center for Science in the Public Interest said warning labels on the fake fat aren't enough protection.

``Your products are making some of your best customers sick, some of them very sick,'' CSPI chief Michael Jacobson wrote Frito-Lay Monday, the same day he asked the Food and Drug Administration to ban olestra.

Olestra manufacturer Procter & Gamble called the claims an ``irresponsible'' attempt to frighten Americans. Frito-Lay said 200,000 bags of ``Max'' chips have sold so far, and only 67 people have called the company to complain of gastrointestinal side effects.

``We are in the business of providing fun foods, not making people sick,'' Frito-Lay spokeswoman Lynn Markley. Mostly, ``the symptoms are similar to if you ate high quantities of vegetables or spicy foods.''

The FDA said it would examine Jacobson's data. But it already placed a warning label on olestra-containing foods because ``we anticipated some individuals would be sensitive to this product and would have gastrointestinal effects,'' said spokesman Jim O'Hara.

The move by CSPI, best known for attacking the fat in movie-theater popcorn and Chinese food, is the latest skirmish in its war on olestra.

Procter & Gamble spent 25 years and over $200 million developing olestra, a chemical made of sugar and vegetable oil that looks like regular fat but has molecules so large and tightly packed that it passes straight through the body without being digested.

Concerned about side effects in studies of olestra, CSPI furiously lobbied the FDA not to approve it. But the agency cleared olestra in January _ with a caveat: Every snack food made with olestra must warn that it can cause ``abdominal cramping and loose stools.''

When Frito-Lay began test marketing olestra-containing chips 10 weeks ago, Jacobson began an advertising campaign urging consumers not to buy ``Max'' chips in the three test cities: Cedar Rapids, Iowa; Grand Junction, Colo.; and Eau Claire, Wis.

Monday, he sent the FDA some of the 192 complaints he has received on a toll-free hot line, including the Colorado boy.

Another caller, Jean Medonic, 49, of Marion, Iowa, said she suffered cramps that felt like labor pains hours after eating half an ounce of chips. ``For 13 or 14 hours ... I was what I consider to be severely ill,'' she said.

Scott Hegwood, 37, of Eau Claire, ate between 3 and 4 ounces and said he was sick for two days: ``I trusted Frito-Lay. ... They broke that trust.''

The consumer group also surveyed at random 500 residents of the three cities, finding 48 people in the 135 households that had tried Max chips also suffered gastrointestinal reactions.

Procter & Gamble, under orders from the FDA to report any consumer reactions, on Friday gave the agency the 67 complaints Frito-Lay received. Although neither firm would provide details of the symptoms or their duration, they insisted most mimicked reactions many people suffer from eating such high-fiber foods as beans.

And some 1,500 consumers have called Frito-Lay to praise Max chips or ask how soon they'll be sold nationwide, Markley said.

Test marketing is scheduled to run through the fall.