South Korea says the number of new coronavirus cases in the country has more than doubled in one day, reports BBC.
Officials said on Saturday that 229 new cases had been confirmed since Friday, raising the total to 433.In a televised address, Prime Minister Chung Sye-kyun described the situation as "grave".
Many of the new cases are linked to a hospital and to a religious group near the south-eastern city of Daegu, authorities have said.
Two patients in South Korea have died so far and there are fears the number will rise.
South Korea has now reported the largest number of confirmed infections after China - 76,288 cases including 2,345 deaths - and the outbreak on the Diamond Princess cruise ship off the coast of Japan which has seen more than 600 cases.
The latest developments came as Chinese health authorities reported a decrease in the rate of deaths and new cases of the coronavirus on Saturday.