Seoul on Wednesday imposed travel bans on parts of Cambodia with South Korea shaken by the torture and killing of a college student there.

"The Bokor Mountain area in Kampot province, Bavet City and Poipet City are designated as travel ban zones," the South Korean foreign ministry said in a statement.

"South Korean nationals visiting or staying in those areas may be subject to penalties under the Passport Act and other relevant regulations. Citizens planning to travel to such areas are therefore strongly advised to cancel their trips," it said.

The ban came after Seoul said earlier in the day that about 1,000 South Koreans are believed to be working in online scam operations in Cambodia.

South Korea is sending a special team, headed by a vice foreign minister, to the Southeast Asian country on Wednesday to discuss cases of fake jobs and scam centres involved in abducting dozens of its nationals.

"It is believed that around 200,000 people of various nationalities are working in Cambodia's scam industry, which targets victims worldwide, including in South Korea," National Security Adviser Wi Sung-lac said.

"A considerable number of South Koreans are also thought to be employed there. While the exact figure is difficult to verify, domestic authorities generally estimate the number at around 1,000."

Seoul has said 63 South Koreans were believed to have been detained by authorities in Cambodia, who were among 80 reported missing. The government was "committed to bringing all South Korean nationals back home", Wi said.

"We are arranging a flight to bring them home... We aim to complete this by the end of the week," he said, adding that there were both "voluntary and involuntary participants" in the scam operations among the 63 detained.

"Most of them should be regarded as having committed criminal acts" for taking part in the schemes, he said, regardless of their initial intentions. (AFP)