SEOUL - South Korean health authorities said on Tuesday they aim to test more than 200,000 members of a church at the centre of a surge of new coronavirus cases as President Moon Jae-in said the situation was "very grave".

South Korea's tally of cases of coronavirus cases rose to 977, fuelling fears the outbreak, which is thought to have begun in the central Chinese city of Wuhan in December, is developing into a pandemic.

A member of a Korean Air cabin crew tested positive for the virus, the airline said, prompting it to shut its office near Incheon International Airport, where the crew briefing room is located.