A Covid-19 outbreak on China's porous border with Myanmar pushed new cases to the country's highest level in six months, according to official data Wednesday, despite tightened border security.
The coronavirus first emerged in central China in late 2019, but a series of strict measures and harsh border restrictions have succeeded in mostly stamping out cases within its borders.
But on Wednesday, 57 new infections were reported -- the highest daily tally since late January -- including fifteen in the city of Ruili, next to Myanmar.
Twelve of those were Myanmar nationals, according to health authorities in Yunnan province, who said blamed the outbreak on the more contagious Delta variant, which was first detected in India.
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 governor said Tuesday that authorities would "resolutely plug all loopholes that may lead to importing the virus".
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.
Ruili has also been placed under lockdown with residents told to stay home and all schools and businesses closed.
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.
The other 42 cases reported Wednesday were imported from overseas.