Korea still lacks the manpower needed to screen out foreign drug users from attaining work visas, it has been claimed - even though it is mandatory for foreign English teacher hopefuls to submit a criminal background check and health data including HIV-AIDS and drug-test results.

Despite the requirements being in place since December 2007, stories of drug-using foreign teachers have continued to capture newspaper headlines.

Six foreign English teachers - three Canadians, two Americans and a New Zealander - were arrested Friday on charges of smoking hashish, a more potent cannabis product than marijuana.