South Korea's Foreign Ministry said the group were working in Yanji in northeastern China, some reportedly for more than ten years, before they were expelled in January.
Officials in South Korea have been briefing Christian organisations about the missionaries' expulsion, Reuters says.
It's unclear why the group were kicked out of China however some say it's because South Korea has just agreed to host a US-owned missile defence system known as the THAAD (example, above) in order to help defend the country against potential aggression from neighbouring North Korea.
North Korea has tested nuclear arms within the past year.
China has argued South Korea's plan to host the THAAD missile system will destabilise the region further rather than maintain peace.
A spokesman for the South Korean government told Reuters there was no signal as of yet that the missionaries were expelled in retaliation to the potential hosting of the missile system.
"There was no official explanation from China," he said. "There is no confirmation that it is related to THAAD."
It's possible the expulsion is unrelated and actually because of China's restrictions on Christianity. It's illegal to practice or share the faith outside of state-monitored churches, forcing millions of Chinese Christians to worship in underground churches.
Christians and lawyers defending them have been imprisoned in unregistered jails and campaigners say believers have also been victim of forced organ harvesting - a practice that was outlawed in China in 2015.
