South Korean authorities have launched an investigation into two Japanese automotive component manufacturers on suspicion of price fixing, according to local reports.

The Seoul Central District Prosecutors' Office is said to have taken on a case brought forward by the Fair Trade Commission (FTC) alleging Mitsubishi Electric and Hitachi Automotive Systems rigged prices in their dealings with South Korean buyers, including Hyundai Motor.

The two Japanese companies are accused of fixing prices since the 2000s for automotive components including alternators and ignition coils.

The move comes as relations between the two countries continued to deteriorate this week following Japan's decision to restrict exports to South Korea of key materials used in smartphone displays and chips.

The move by Japan is understood to have been in retaliation to a South Korean court decision ordering Japanese firms to compensate South Korean victims of forced labour during the World War II.

Japan maintains the dispute was settled by a 1965 treaty which normalised ties between the two countries. Japan also removed South Korea as a preferred trading partner last week.

South Korean prosecutors last month also fined four Japanese companies, Mitsubishi, Hitachi, Denso and Diamond Electric, a total of totaling KRW9.2bn (US$7.6m) following a separate investigation launched in 2014.