An annual Korean language proficiency test held in Vietnam will not be held this year due to a surge in illegal workers in South Korea.

The Human Resources Development Service of Korea said on Friday that the South Korean government did not extend the memorandum of understanding (MOU) with Vietnam on the employment of foreign workers.

The service said that under the decision, the annual test will be suspended until those who have already passed the test are all employed in South Korea.

About 60-thousand to 70-thousand foreigners take the exam every year. Approximately 14-thousand test takers passed it last year, of which 28-hundred were hired in South Korea.

As of the end of August, the number of illegal Vietnamese workers in South Korea stands at 15-thousand. The Vietnamese marks the largest group among foreign workers from 15 different nations.