Olympus Corp. has defended the quality of its endoscope which a group of journalists allege caused in-hospital infections, saying there has been no confirmation of a link between the use of the device and the disease.

"There is no fact that the cause has been determined regarding the matter," Olympus said in a statement released Tuesday.

[Olympus' U.S. website]

Olympus said, "We are faced with civil lawsuits in connection with a duodenum endoscope. We will make our cases in court regarding what has been reported."

The International Consortium of Investigative Journalists said there had been nearly 200 cases of "superbug" infections following the use the TJF-Q180V duodenum endoscopes in Europe and the United States between 2012 and 2015.

The ICIJ also revealed that an Olympus executive in Tokyo sent an email in 2013 to the company's U.S. arm stating, "It is not need (needed) to communicate to all the users actively" about the possibility of infection due to the use of Olympus duodenum endoscopes.

"You should communicate with the user who has asked a question," the email, which was presented as evidence in lawsuits, said.

Olympus did not mention the email communication in the statement.

Several of the individuals infected with antibiotic-resistant bacteria died, though it is not certain whether their deaths were the direct result of infection, said the consortium of which Kyodo News is a partner.

The infections may have occurred due to difficulties in cleaning and sterilizing the equipment.

U.S. website Kaiser Health News has reported that at least 35 people have died since 2013 after developing infections linked to Olympus duodenoscopes.

Around 50 lawsuits have been brought against the major Japanese optical equipment maker seeking compensation over the superbug infections.

In 2015, the U.S. Food and Drug Administration issued a warning to the company for failing to promptly report the bacterial infections even though it was aware of them in November 2012.

The TJF-Q180V duodenoscopes that are believed to have caused the infections have been sold since 2010 in Europe and the United States, according to a report compiled by a U.S. lawmaker and lawsuit documents.

More than 190 people were infected in 17 medical institutions in the United States, the Netherlands, France and Germany, they said.

European authorities, suspecting that the infections could be the result of difficulties in cleaning the endoscopes, ordered Olympus to warn equipment users of the possibility.

After the safety warning was issued by Olympus in Europe in January 2013, the number of infections in the region was about 50, significantly lower than the around 140 in the United States.

Separately, data analysis by the ICIJ conducted since this spring showed that more than 5.4 million cases of health problems linked to medical devices, including Olympus duodenoscopes and other manufacturers' products such as pacemakers and intrauterine devices, were reported to the FDA over the past 10 years.