South Korea has said it will tighten social distancing rules across most of the country this week, warning that its worst-ever Covid-19 wave might spread further in the summer holiday season, Reuters reports.

The curbs will be increased to level three on a four-level scale, which will mean a 10pm dining curfew and a ban on gatherings of more than four people, from Tuesday for two weeks for most areas except for some small counties.

"What's most concerning is the virus' recent spread in the non-capital areas," President Moon Jae-in told an intra-agency meeting reviewing efforts in the campaign against the coronavirus.