Beijing, China - China's government on Thursday advised its citizens to exercise caution when traveling to the US and to avoid Seattle's main airport over "malicious" border checks.

Around 20 Chinese scholars planning to attend academic conferences were "recently" denied entry by US Customs and Border Protection at Seattle-Tacoma International Airport despite holding valid visas, according to a statement from China's foreign ministry.

CBP did not respond immediately to a request for comment, and more information about the alleged entry denials, which was sent by the AFP outside of US business hours.

The Chinese Foreign Ministry said that, "in light of… malicious interrogation and harassment targeting Chinese scholars" at Seattle airport, authorities "advise individuals planning to travel to the United States in the near future to heighten their safety awareness."

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The statement advised travelers to respond in a "calm and rational manner" if they were questioned by US border authorities and to "avoid entry" through Seattle Airport.

The warning comes ahead of a planned mid-May visit to Beijing by President Donald Trump, which was delayed for several weeks after the US and Israel launched a devastating war of aggression against Iran.

It also comes about a week after the death of a Chinese researcher in Michigan, who had been questioned by federal law enforcement investigators mere hours earlier, triggered outrage in Beijing.