A new nationwide program to locate missing children by printing their pictures and biographies on milk cartons has more than doubled the number of calls to the National Center for Missing and Exploited Children, a spokesman said yesterday.

"On the typical day three weeks ago we'd receive four or five calls a day from individuals who thought they recognized a missing child," said Jay Howell, executive director of the center. "Now, we're getting 10 calls a day, and we believe the increase is attributable to the milk cartons," which include a toll-free number for the center.

Millions of half-gallon milk cartons, each with the names and pictures of two missing children, have been printed and distributed to stores across the country, according to H.R. Wilkinson, president of the National Child Safety Council, which organized the campaign.

Wilkinson said the campaign has been joined by hundreds of dairies that want to help locate the thousands of children missing each year and reunite them with their families. The program has been broadened to include half-pint school milk cartons, which will carry a "super hero figure" called Safetypup that gives tips to children on how to avoid being abducted.

Howell said that, of the 4,000 to 20,000 children abducted each year, about 2,000 are missing for a substantial period of time, and the rest are usually returned after suffering some kind of harm, frequently sexual abuse.

He said that a campaign in California led to the return of a 13-year-old girl who had run away from home and who spotted her picture on a milk carton and called her family. No missing children have been found as a result of the three-week-old campaign, he said.

Wilkinson said similar regional campaigns came to the attention of the National Child Safety Council, a nonprofit child safety organization, and prompted it to pursue the idea on a nationwide scale. He said the pictures will change every month.

"The majority of criminally abducted children are taken far from their homes, often clear across the country," Wilkinson said. "Even if one child is found due to this program, we will consider it well worth the effort."

Larry Johnson, public relations manager for Safeway Stores Inc., said that about 231,000 half-gallon containers of the company's milk will be printed with the pictures each week for distribution in 234 stores between Virginia and Pennsylvania. The cartons will start appearing on shelves this weekend, he said.

"We are very excited about this," Johnson said. "It's a tremendous opportunity to reach out to these kids. Hopefully they're out there somewhere."