The number of foreign residents staying in the country illegally has topped 400-thousand for the first time, accounting for about one in five non-citizens nationwide.

According to data by the Korea Immigration Service posted on its website on Tuesday, the total number of foreign nationals exceeded two-point-17 million as of the end of September, up two-point-three percent from a month earlier.

Of this total, over 402-thousand had overstayed their visa and remained in the country without authorization, rendering them eligible for deportation.

The figure rose steadily by around three-thousand each month this year before spiking by 74-hundred in August and 82-hundred in September. The pandemic situation abroad and travel restrictions in South Korea are considered motivating factors for the overstays.

The number of illegal foreigners topped the 200-thousand mark in 2014 and surpassed 350-thousand in 2018.