Mystery 'sonic influence' in China prompts U.S. warning to citizens

 An American citizen working at a U.S. consulate in China has reported suffering from "abnormal" sounds and pressure leading to a mild brain injury, the U.S. embassy said on Wednesday and China said it was investigating the incident.

The embassy, which issued a health alert to Americans living in China, said it could not link the case to health problems suffered by U.S. government staff in Cuba dating back to late 2016.

In Washington, U.S. Secretary of State Mike Pompeo said the United States was concerned about the "serious medical incident" and raised it with China's visiting State Councillor Wang Yi.

"We notified China of what took place as best we know it and they have responded in a way that is exactly the right response," Pompeo told a news conference with Wang.

"We're working together to resolve (this) ... I hope we can figure it out," Pompeo said.

Earlier, he told Congress that the incident in China was "medically similar" to one suffered by U.S. diplomats in Cuba.

Wang, speaking through a translator, said Beijing was investigating the incident, adding "we haven't found any organization or individual has carried out such a sonic influence."

"We don't want to see that this individual case will be magnified, complicated or even politicized. We hope people will not associate it with other unnecessary matters," he cautioned.

The unnamed U.S. citizen assigned to the consulate in the southern city of Guangzhou had reported various "physical symptoms" dating from late 2017 to April this year, the U.S. embassy in Beijing said in an email.

The worker was sent to the United States for further evaluation. "The clinical findings of this evaluation matched mild traumatic brain injury (MTBI)," the embassy said.

Pompeo said medical teams were heading to Guangzhou to investigate the incident.

The U.S. government on Wednesday issued a health alert to Americans in China, warning them about what it described as "subtle and vague, but abnormal, sensations of sound and pressure".

"While in China, if you experience any unusual acute auditory or sensory phenomena accompanied by unusual sounds or piercing noises, do not attempt to locate their source. Instead, move to a location where the sounds are not present," the emailed alert said.

China's nationalistic Global Times tabloid said in a commentary late on Wednesday that it was "very inappropriate" that the United States issued a public health alert despite only having a "vague understanding" of the situation.

It said it was "inconceivable" that China would carry out targeted attacks on the health of foreign diplomats.

"We firmly believe that there is not much possibility of any 'background' to the American consulate official's 'brain injury'," it said.

The U.S. government in October expelled 15 Cuban diplomats from the United States for what it said was Cuba's failure to protect staff at the U.S. embassy in Havana from mysterious health incidents at one point thought to possibly have been acoustic "attacks".

The staff there reported symptoms including hearing loss, dizziness, fatigue and cognitive issues, though Cuban officials dismissed the idea of acoustic strikes as "science fiction" and accused Washington of slander.

The cause of those incidents remains unresolved.

The Canadian government in April said it would remove families of diplomats posted to Cuba after Canadian personnel there in 2017 also reported similar health symptoms.