The U.S. Food and Drug Administration said on Tuesday it is investigating a growing number of reports of non-viral hepatitis in Hawaii that have led to 11 hospitalizations and one death.

The FDA said the common link between at least some of the cases appears to be a dietary supplement called OxyElite Pro, which is distributed by USPLabs LLC of Dallas, Texas and sold throughout the United States via the Internet and retail stores.

The FDA said there have been 29 reports of the liver-damaging condition, with 24 sharing the OxyElite connection. Two patients have received liver transplants.

The Centers for Disease Control and Prevention is looking nationally at other cases of liver injury that may be related, the FDA said.

USPLabs said in a statement that it "stands by the safety of all of its products," adding that "the cluster of liver issues in Hawaii is a complete mystery."

The company said that "out of an abundance of caution" it will cease distributing OxyElite Pro until the investigation is complete.

Non-viral hepatitis is not infectious. It can be caused by alcoholism or drugs, including excess doses of prescription medications or over-the-counter products such as Tylenol.

FDA spokesman Steven Immergut said the agency has recalled "a couple" of technical experts who had been furloughed due to the federal government shutdown. The CDC said it had already begun responding to the situation at the time of the shutdown and has not had to change its staffing.

Several hundred FDA investigators have been furloughed as a result of the shutdown, now in its eighth day. Those still working are prioritizing their activities based on public health needs "and are being deployed to situations like this that require immediate attention," Immergut said.

The FDA said the company informed the agency that it believes counterfeit versions of OxyElite Pro are being marketed in the United States and it is investigating. When asked to confirm the FDA's statement, USPLabs declined to "speculate."

USPLabs said it knows of "no credible evidence" linking OxyElite Pro to liver issues. The company said it sells several versions of OxyElite Pro and that the ones being investigated are the original version, OxyElite Pro with DMAA, and two of its later versions, OxyElite Pro with the "Purple Top" and OxyElite Pro Super Thermo Powder.

It said it stopped making the original version in early 2013 after the FDA cracked down on dietary supplements containing DMAA, a stimulant that the agency said can cause heart attacks.

Last year, the FDA issued warning letters to companies that make DMAA-containing dietary supplements to take them off the market.

This past July, as a result of follow-up legal action by the FDA, USPLabs destroyed its DMAA-containing products, including OxyElite Pro with DMAA and Jack3d - estimated to have been worth more than $8 million at the retail level.

The CDC and Hawaii Department of Health are spearheading the investigation into the source of the hepatitis outbreak. The FDA is reviewing medical records and histories of patients identified by the Hawaii health department. The agency said it is also analyzing the composition of product samples collected from some of the patients.

"In the interest of protecting public health, we are moving quickly to learn as much as possible," the FDA said in a statement. "We recognize that people will be concerned about these illnesses, and we will provide updates as the investigation develops."