Such voluntary disclosure was required as the new coronavirus pneumonia which first broke out in Wuhan of central China's Hubei province has been put under quarantinable infectious disease management with the approval of the State Council.
The move was to curb the cross-border spread of the new coronavirus and to safeguard public health, according to a joint statement released by the General Administration of Customs and National Health Commission.
Those who have made voluntary reports should collaborate with customs officers in following health quarantine which involves temperature screening, medical checks and medical investigation, said the statement.
Passengers, once feeling sick in transit, should also timely report their situations to passenger crew. The persons in charge of the relevant vehicles should provide personal protection gear to passengers and report timely to the customs authorities at the entry and exit ports.
People going abroad or coming to China should maintain good personal hygiene, for instance washing their hands frequently, wearing masks and avoiding close contact with people suffering from acute respiratory infection.
Sickened passengers must immediately seek medical care and describe to doctors their recent trips.
China's customs authority will adjust port control measures based on the progress of the outbreak, said the statement.