The number of foreigners overstaying in South Korea increased 10 percent on-year in May, as travelers and migrants were stranded by strict border controls around the world due to the novel coronavirus, data showed.

The number of foreigners illegally staying in the country reached an all-time high of 396,654 in the month, according to the Korea Immigration Service.

Of them, about 296,000, or 75 percent, were visitors who entered the country without visas for a 90-day stay. The number of illegal short-term visitors increased by 11 percent from the same month in 2019.