Since 2005, South Korea has required foreign nationals with E-9 visas to pass the Korean language test. When they pass the test, they are allowed to be registered to work here.
As Korean language lessons were not handy for many of the migrant workers in Asian countries, the ministry comprised the test from a pool of already-disclosed 2,000 questions.
From the first-half of this year, however, the test will include questions that have not been disclosed, officials at the Ministry of Employment and Labor said.
"While the Korean language test has helped increase fairness and transparency in selecting migrant workers, there have been opinions that the test has a limit in making the workers proficient in Korean," a ministry official said.
It wasn't immediately made clear when the new test will start.
The ministry said it will gradually increase the proportion of "undisclosed questions" in the Korean language test to prevent a sharp decline in the number of workers who pass the test.
South Korea plans to hire some 48,000 non-professional foreign workers this year, up from 34,000 in 2010, according to the ministry's Web site.
Those workers are mostly hired by employers in the sectors of manufacturing, agriculture, livestock and fishing farms, it said.