SEOUL, Sept. 18 (Xinhua) -- South Korea's trade ministry said Wednesday that it implemented the removal of Japan from its whitelist of trusted export partners beginning midnight.

The Ministry of Trade, Industry and Energy announced the removal decision on Aug. 12, and had since gone through necessary procedures, including the collection of public opinion and the legality deliberation.

According to the collected public opinion, 91 percent of respondents was in favor of the removal implementation, the ministry said.

Under the revised regulation, South Korea regrouped its trading partners into three from the previous two, placing Japan in the in-between group, where Japan was the only country to be placed until now.

South Korean companies shipping strategic materials to Japan would be required to go through more complicated documentations, the approval for which would take about 15 days. It is longer than the previous five days.

Local exporters would also face tougher procedures to win comprehensive approval for shipping strategic materials to Japan for an expiry of two years, shorter than the previous three years for the trusted export partners.

It came a week after South Korea filed a complaint with the World Trade Organization (WTO) against Japan over its restrictions on the export to South Korea of three materials vital to produce memory chips and display panels, the mainstay of the South Korean export.

The export restrictions by Japan were made in early July after South Korean top court's ruling last year that ordered some of Japanese companies to compensate the South Korean victims who were forced by Imperial Japan into hard labor without pay during the 1910-1945 Japanese colonization of the Korean Peninsula.

In August, Japan dropped South Korea off its whitelist of trusted trading partners that are given preferential export procedures. In response, Seoul decided to take Tokyo off its whitelist of trusted export partners last month, enforcing it from Wednesday.

Japan claimed that all colonial-era issues were settled through the 1965 treaty that normalized diplomatic relations between Seoul and Tokyo after the colonization, but South Korea said the accord did not involve individuals' right to reparation.