Cuba said Thursday the United States is continuing to withhold important information that could help in the investigation into mysterious incidents that have injured some two dozen Havana-based American diplomats, including some with brain damage, since late 2016.

After meeting with U.S. officials at the State Department, members of a team Cuba assembled to look into the incidents said their requests for patient records and other information had again been rebuffed and rejected anew Washington's assertions that the injuries were caused by targeted attacks.

"The Cuban side is completely unable to support the hypothesis of health attacks and brain damage as reported by the State Department," said Dr. Mitchell Valdes Sosa, chief of the group of Cuban scientists and physicians. "Nothing was presented that could add up to sustain such a thing."

The Cuban delegation renewed calls for the State Department to release to it specific medical records and other data about the victims in order for it to be studied.

It also repeated demands that Washington stop referring to the cause of the symptoms as "health attacks" in the absence of definitive proof and denounced reports citing U.S. officials as saying that investigators may be narrowing their suspicions about the cause and culprit behind them.

"The State Department has been treating theories as if they were facts," said Johana Tablada, a senior Cuban diplomat who led the team.

Thursday's meeting was held as American authorities search for answers into mysterious "health attacks" that began two years ago in Havana and amid growing frustration among national security agencies and members of Congress about the lack of answers on what and who caused the injuries.

Recent reports have suggested investigators are focusing on the possibility that some sort of microwave device may be responsible and that Russia, which has long had close ties with Cuba, is the leading suspect for the attacks.

The State Department, however, has denied that any conclusions had been drawn.

"We still don't know the cause, we still don't know what or who is responsible for health attacks that took place that affected our personnel in Cuba," spokeswoman Heather Nauert told reporters on Thursday.

NBC News, citing U.S. officials and others briefed on the investigation, reported this week that Russia is the main suspect in an investigation into the attacks that led to brain injuries in both Cuba and China.

That suspicion, they say, is backed up by evidence from communications intercepts amassed during a lengthy and ongoing investigation involving the FBI, the CIA and other U.S. agencies. But the evidence is not conclusive enough to put the blame on Moscow.

Nauert did not address a Cuban request for "a dispassionate examination of health reports of U.S. diplomats in Cuba according to the rules of science" but said the meeting would "involve private medical information that is coming forth from some of our people."

The Cubans, however, said no such information was shared beyond what was previously available in a published medical journal report, which they and others have found to be inconclusive

Those reports have raised protests from Cuba, which does not dispute the symptoms but insists there is no evidence to support any assertion that they were caused by premeditated attacks on its soil or that there is evidence to point too a perpetrator.

Cuba has repeatedly denounced the U.S. accusations as politically motivated and unproven and did so again on Thursday. "Stop using the word 'attack.'"

Twenty-five U.S. Embassy workers in Cuba, as well as one at the U.S. consulate in Guangzhou, China, have been affected by mysterious health incidents that began in the fall of 2016. The range of symptoms and diagnoses includes mild traumatic brain injury, also known as concussion.

The last case from Havana was confirmed in June. The U.S. said two embassy staffers were affected in a single occurrence in late May in a diplomatic residence at which both officers were present. Those were the first confirmed cases in Havana since August 2017.

Thursday's meeting was organized after Cuba complained that Washington has refused to share key details about the affected Americans' medical conditions. Sosa said the talks were a "productive and very cordial scientific meeting but we received no new information."

In classified briefings with congressional aides and lawmakers last week, the officials repeated that they had not come to any conclusions about what caused the injuries or who might be responsible for them, according to officials familiar with the meetings.

Initial speculation had centered on some type of sonic attack, owing to strange sounds heard by those affected. But an interim FBI report in January found no evidence that sound waves could have caused the damage.