Multinational enterprises operating in South Korea accounted for two-thirds of unpaid tariffs imposed between 2008 and 2012, data showed Sunday, drawing calls for the tightening of customs-related probes.

According to the Korea Customs Service data submitted to parliament, the amount of unpaid tariffs imposed on foreign firms by fixing transfer price came to 786.5 billion won ($740.5 million) over the cited period.

The number accounts for some 65 percent of the country's combined evaded tariffs of 1.2 trillion won levied from 2008 to 2012.

The transfer price refers to the value set on certain goods and services traded between the foreign-based holding companies and their local affiliates.

Fixing such prices has been considered as one of most frequently used methods by multinational companies to evade duty and taxes.

Of the 2,625 companies investigated by the customs authority for allegedly evading paying duty from 2008 to 2012, multinational firms accounted for 371, or 15 percent of the total, the data also showed.

Meanwhile, of the 285.2 billion won tariff imposed on multinational companies in South Korea in 2011, only 25 percent of the amount was successfully collected, implying such firms are not abiding by local customs authority's orders.

"The customs agency must bolster its probe on tax-evasion attempts from transfer-price fixing, and make efforts to collect unpaid taxes," said Rep. Lee In-young of the main opposition Democratic Party. (Yonhap News)