Health Canada and the Consumer Product Safety Commission in the U.S. have launched investigations into a new kind of Pampers diapers that some parents say are causing rashes and blisters on their children.

Health Canada issued a short advisory on Wednesday that read: "Health Canada has recently received two complaints of rashes that may have resulted from the use of Pampers Dry Max Diapers. Health Canada officials immediately contacted Procter and Gamble to follow up, and the investigation is now ongoing."

It added that it is working with U.S. health officials in the investigation.

Several parents who are unhappy with the new diapers have set up a Facebook group called "Pampers bring back the OLD Cruisers/Swaddlers." The group now has more than 4,000 members.

Some members report that their babies developed blisters, rashes and yeast infection and what appears to be chemical burns after using new Pampers Swaddler and Cruisers diapers that have a thinner, more absorbent filling, called Dry Max.

The diapers were officially launched in the U.S. in March, though Procter and Gamble started selling some of the new diapers without changing the labelling in late 2009.

The parents insist the problems started only when they used the new diapers and disappear when they switch brands.

P&G has called the new diaper formulation its biggest diaper innovation in 25 years, and says the new product went through extensive testing before its release.

"There's no evidence that a single baby has experienced a serious skin safety issue as a result of Dry Max," said Bryan McCleary, a spokesman for P&G's baby care division, noting as well that diaper rash is very common among babies.

He insisted that the company the amount of complaints it's seeing is in line with expectations. "It's one severe rash complaint for every 6 million diaper changes," McCleary said.

A statement on the Pampers website insists Dry Max diapers are not much different from their predecessors: "Our Dry Max diapers use the same type of ingredients and materials as our other diapers and in fact, many other disposable diapers on the market. The key difference is simply in how we designed and produced the diaper itself."

It notes that P&G test the safety of all ingredients used in its products. "We thoroughly evaluate for systemic toxicity, skin irritation or skin sensitization (skin allergy)."

Pediatric dermatologists contacted by Pampers also insist that the product is as safe as the previous version, including Dr. Loraine Stern, a clinical professor of pediatrics at the UCLA School of Medicine.

"I have seen absolutely no increase in rashes since the introduction of the newer model," Stern wrote in a statement provided to Reuters by Pampers.

"The pictures on the Internet show what looks like classical rashes, not chemical burns. I have full confidence in recommending that my patients continue to use Pampers with Dry Max."

Health Canada says it will post additional information on its investigation as soon as it is available.