China has expelled 32 South Korean Christian missionaries, a South Korean government official said on Saturday, amid diplomatic tension between the two countries over the planned deployment of a U.S. missile defense system in the South.

The 32 were based in China's northeastern Yanji region near the border with North Korea, many of whom had worked there more than a decade, South Korean media have reported.

South Korea's foreign ministry said on Friday it briefed Christian groups on the case of the missionaries, adding that they were expelled in January.