China has advised its citizens travelling to the US to avoid a Seattle airport, citing “malicious interrogation and harassment” of some 20 Chinese academics.

The Chinese foreign ministry said on Thursday that the academics had valid visas and were going to a conference but were denied entry after “unreasonable interrogation” by US border officers at Seattle-Tacoma International Airport.

The ministry said that any citizens planning to travel to the US in the near future should improve their awareness of security, avoid Seattle-Tacoma International Airport and “carefully review US entry regulations in advance to make all necessary preparations”.

The travel reminder, issued by the foreign ministry and Chinese diplomatic missions in the United States, was made “in light of consecutive incidents of malicious interrogation and harassment targeting Chinese scholars” at the Seattle airport, the notice added.

Liu Pengyu, a spokesman for the Chinese embassy in Washington, said the US had “overstretched” the concept of national security to “groundlessly” interrogate and harass Chinese scholars and students.

He warned that such actions had infringed on their legitimate rights and would have a chilling effect on people-to-people exchanges.

“China will continue to take ... necessary [measures] to firmly defend Chinese citizens’ legitimate and lawful rights and interests,” Liu said in a statement.