SEOUL (XINHUA) - South Korea reported 51 new coronavirus cases on Wednesday (June 24), up from 46 new cases on Tuesday as the number of infections in the country continues to rise.

Of the 51 new cases, 31 were locally transmitted and 19 of them were reported in the densely populated Seoul and nearby metropolitan areas, the Yonhap news agency reported.

Cluster infections on a Russia-flagged cargo ship docked in the south-eastern city of Busan, the country's second-largest city, became a new source of concern for health authorities and raised a red flag about how quarantine procedures are handled at ports.

At least 16 sailors aboard the Ice Stream tested positive for Covid-19. Another sailor on a Russian-flagged vessel nearby was also infected with the virus.

Officials have permitted the Ice Stream to disembark at the port and unload cargo because the ship had submitted falsified electronic documents over its quarantine records.

The operator of the ship also failed to inform South Korea that three of its sailors showed symptoms of high fever.

The captain who alighted from the ship a week earlier was also infected with the virus.

A total of 170 port workers who had been in contact with the sailors from the Russian vessel have been placed in isolation.

South Korea's health officials said starting from Wednesday, they will begin to board ships arriving at Busan ports to better carry out quarantine checks.

South Korea was once the poster child in the battle against the coronavirus for its success in bringing down the cases to a single digit.

But the number has bounced back after it relaxed social distancing rules in May as the country grapples with a second wave of infections.

The total number of cases now stands at 12,535 with 281 deaths.