The government has discontinued sales of some 30 diabetes drugs after traces of a possible carcinogen were found in the products. 

The Ministry of Food and Drug Safety said on Tuesday that an inspection revealed 31 out of 288 types of the diabetes drug metformin in circulation contained the possible carcinogen N-Nitrosodimethylamine(NDMA) beyond permissible levels.

The ministry, however, said that NDMA, classified by the World Health Organization as a "possible carcinogen," was not found in the raw materials for the drugs beyond acceptable levels. 

The ministry suspended production and sales of the 31 medications and restricted prescriptions, although it said these drugs are very unlikely to cause any harm in humans. 

The Ministry of Health and Welfare also took steps to ensure pharmacies and hospitals do not prescribe and dispense the affected drugs.