SHANGHAI (REUTERS, AFP) - The authorities in China's south-western province of Yunnan reported 15 new confirmed locally transmitted coronavirus cases for Tuesday (July 6), with all cases in the city of Ruili, bordering Myanmar.

The 15 confirmed cases compared with three confirmed locally transmitted cases a day earlier.

Two of the cases confirmed for July 6 had previously been identified as asymptomatic cases, which China does not classify as confirmed cases.

The other 13 were identified through mass testing in the city of Ruili, the Health Commission of Yunnan Province said in a statement.

Ruili is a major crossing point from Muse in neighbouring Myanmar, which has seen escalating unrest since a February 1 military coup, raising fears that people will flood across the border into China to escape the violence.

The provincial authorities have prevented individuals from leaving or entering Ruili without special permission since July 5.

It is the second time in four months that Ruili has been locked down over the discovery of cases imported from Myanmar, after another small outbreak in April.

China closed the main bridge and crossing to Myanmar in March as cases surged across the border.

Authorities have also deployed more soldiers and increased patrols to prevent illegal border crossings and cracked down on human trafficking to prevent an influx of refugees.

All 210,000 residents in the city had been tested by Monday night, according to officials, with 90 cases reported in the city over the past week.

The provincial governor said Tuesday that authorities would "resolutely plug all loopholes that may lead to importing the virus".

Yunnan province also reported two new locally transmitted asymptomatic cases for July 6, and one new asymptomatic case imported from abroad, the statement said.

The last outbreak of local Covid-19 cases in China was in the southern Guangdong province in the middle of last month.