Five Thai tourists were among more than 60 people injured in a 105-vehicle pile-up on the highway to South Korea's largest international airport on Wednesday morning, the Foreign Ministry said.
Ministry spokesman Sek Wannamethee said the visitors were in a van driven by a South Korean.
The accident occurred at 9.34am (7.34am Thailand time) on the Seoul-bound lane of Yeongjong bridge that forms part of the main expressway linking Incheon airport with the capital.
The Thais were sent to a hospital in Incheon. One of them is still in an intensive care unit, two others are in an emergency room and the other two have been released, the spokesman quoted a report from the Thai embassy in South Korea as saying.
The embassy had contacted the families of the injured and is finding out whether they have travel insurance, he added.
Byeon Tae-u of the Incheon Fire and Safety Management Department said the crash was likely aggravated by thick fog and icy road conditions. It was not immediately known what started the pile-up.
An Incheon police station spokesman said the pile-up involving 105 vehicles appeared to have started when a limousine ran into the back of a car.
Officials and Yonhap news agency said at least 68 people were injured, including seven Chinese, two Vietnamese and two Filipino visitors. The other four foreign nationals injured were from Japan, Russia, Bangladesh and Switzerland.