SHANGHAI (REUTERS) - Mainland China reported 32 new Covid-19 cases on Thursday (Sept 17), marking the highest daily increase in more than a month and up sharply from nine cases reported a day earlier, the Chinese health authority said on Friday.

Although the latest increase still remains well below the peaks seen at the height of the outbreak in China early this year, it is the biggest since Aug 10 and suggests continued Covid-19 risks stemming from overseas travellers coming into the country as the pandemic rages on in other parts of the world.

The National Health Commission (NHC) said in a statement that all new cases were imported infections, 13 of which were in the north-western Shaanxi province and another 12 in Shanghai.

Mainland China has not reported any local Covid-19 infections since mid-August.

The commission did not offer further breakdowns, but Shanghai's city government said on Friday that nine of the 12 new patients - all Chinese nationals - flew into the city on a flight from Manila on Wednesday.

Shanghai did not specify which airline operated the flight with those nine patients, but it said in a separate statement that two China Eastern flights connecting Shanghai and Manila had been suspended due to Covid-19 risks.

Carriers are ordered to suspend international routes when passengers on one of the flights are confirmed as Covid-19 patients.

The NHC also reported 20 new asymptomatic cases, also up from 14 a day earlier, though China does not classify these symptomless patients as confirmed Covid-19 cases.

The total number of Covid-19 cases for mainland China now stands at 85,255, while the death toll remains unchanged at 4,634.