BEIJING : A key Chinese port city near the border with North Korea has launched regular Covid-19 testing for all 7.5 million inhabitants as its isolated neighbour grapples with a spiralling outbreak.

China has stuck to a hardline, zero-Covid approach that has left the capital Beijing under a mosaic of restrictions and confined most of the 25 million residents of Shanghai to their homes for weeks.

Across the border, impoverished, nuclear-armed North Korea has announced more than 1.7 million infections since last week, putting Chinese authorities on edge.

Officials in Dalian -- a port around 300km (190 miles) from North Korea -- implemented a regular testing policy on Tuesday for all residents after logging a handful of cases in recent days.

City authorities said men and women will be tested on separate days, sparking confusion.

Authorities told state media that the gender-segregated testing would allow them to monitor the same household multiple times per week, seemingly assuming nuclear family units consisting of one man and one woman.

"This is the first I've heard of splitting Covid tests by gender," a social media user wrote on the Weibo platform.

Men have been told to get tested on Tuesdays, and women on Thursdays with both then tested again on Saturdays.

"Testing members of the family at different times will better help to... raise the sensitivity and timeliness of the tests," a health official said at a press briefing this week.

Other Chinese cities also tightened restrictions in the wake of North Korea's blooming outbreak, with the northern port of Tianjin partly closing its subway system "in accordance with the needs of disease control", state broadcaster CCTV reported Wednesday.

Residents in parts of the capital remain under work from home orders as the city reported 69 new local cases.

There were a few signs of easing in Shanghai, where some locked-down residents mocked an announcement that the megacity had "achieved zero-Covid at the community level", even as they remain stuck at home.

After parts of Shanghai were doused in a haze of chemical disinfectant in recent weeks, a city official in charge of disinfection warned against "excessive" sterilisation.

Zhu Renyi urged workers not to spray disinfectant on people, use drones to spritz outdoor areas or put sterilising tablets into the sewers.

  - AFP