SHANGHAI, June 16 (Xinhua) -- Shanghai reported three new imported COVID-19 cases and no increase in locally transmitted cases on Monday, the municipal health commission said Tuesday.

All of the three imported cases involve Chinese nationals. One of the patients departed from Singapore on June 11 and arrived at the Shanghai Pudong International Airport on the same day. The person exhibited symptoms during isolated observation and was later tested positive for COVID-19.

The other two patients both departed from the United States on May 31 and arrived in Shanghai on June 2. Both of them exhibited symptoms during isolated observation and were later tested positive.

The patients have been receiving treatment in designated hospitals. A total of 118 close contacts on the flights have been put under quarantine.

As of Monday, Shanghai had reported a total of 354 confirmed imported cases and 341 locally transmitted cases.