Beijing will upgrade its novel coronavirus prevention measures regarding international travelers starting Wednesday as China is facing mounting pressure from imported cases, while the domestic outbreak has been temporally contained.

China has already established three lines of defense at the ports of entry, community and medical facilities that can effectively prevent imported cases from causing the spread of novel coronavirus again, Wu Zunyou, an epidemiologist at the Chinese Center for Disease Control and Prevention, said at a news conference held in Beijing on Tuesday.

Of the 78 new confirmed cases on Monday, 74 were imported, according to the National Health Commission. The total number of imported cases reached 427 by Monday and 47 are foreigners, according to the Foreign Ministry.

Of the 74 imported cases on Monday, 31 were found in Beijing. Facing a grave epidemic control situation, the Beijing government announced on Tuesday that from midnight on Wednesday, all people entering China via ports in Beijing will be quarantined in designated facilities in the city for 14 days regardless of their final destinations, as well as tested for the virus.

The pressure of screening for infected travelers has been increasing, particularly in transportation hubs and major port cities, Wu said.

"To effectively prevent the outbreak from hitting the country again, three lines of defense have been established," Wu said, adding that the domestic outbreak has been temporally contained.

The first line defense is at the ports of entry where international travelers are required to receive temperature check, medical checkups and report their travel history. If people are showing symptoms of the novel coronavirus, they will then be sent to medical facilities for treatment, Wu said.

The 14-day quarantine is the second line defense. The move is to ensure people can receive treatment as soon as they start to show symptoms of infection during the virus' incubation period, he said.

Even if the two lines of defense both fail, medical staff and facilities around the country would effectively handle novel coronavirus patients after gaining experience when the outbreak was severe, he said.

So far all imported cases have been found by the first two lines of defense, Wu said, adding that he believes the three lines can prevent imported cases from causing a second round of outbreak.