Pompeo testified before the House Foreign Affairs Committee on Wednesday that the symptoms were "very similar" and "entirely consistent" with ailments that sickened 24 US diplomats or family members in Havana from late 2016 to summer 2017. The Trump administration has called the Cuba incidents "deliberate attacks" but has still not determined what caused them.

The US diplomats in Havana told officials they heard painful, high-pitched noises in 2016 and then suffered headaches, dizziness and nausea, and struggled to concentrate.

The employee in China started experiencing the symptoms late last year through April, said Jinnie Lee, the embassy spokeswoman. The embassy learnt of the diagnosis on May 18, she said, and officials are taking the issue "very seriously."

Investigators were confounded by the situation in Cuba. Researchers at the University of Pennsylvania, which the State Department asked to investigate, found symptoms of a concussion although those affected hadn't bumped their heads. They had heard the noises in their homes or hotel rooms.

The unexplained incident sank the relationship between the US and Cuba, which had only restored diplomatic relations in 2015 after more than half a century. The State Department pulled most of its personnel from the US Embassy in Havana and expelled 17 Cuban diplomats in Washington.

Former Secretary of State Rex Tillerson referred to the situation last year as "targeted attacks," although investigators struggled to find evidence of a sonic weapon. Cuban officials denied involvement.

Pompeo said the Chinese government was notified of the latest report and that it pledged to honor its international commitments to protect foreign diplomats.

Lee, the embassy spokeswoman, said the Chinese government has "assured us they are also investigating and taking appropriate measures" related to the case in Guangzhou, a sprawling port city on the country's east coast.

Wednesday's health alert to US citizens came as Chinese Foreign Minister Wang Yi prepares to meet with officials in Washington. He's expected to discuss trade between the world's two largest economies as they try and broker a deal that averts heavy tariffs.

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The alert advised citizens to see a doctor if they suffer from any medical problems during or after their stay in China.

And it had a less conventional suggestion: "If you experience any unusual acute auditory or sensory phenomena accompanied by unusual sounds or piercing noises, do not attempt to locate their source," it said. "Instead, move to a location where the sounds are not present."

MCT