SEOUL –

South Korea's economic policy chief said Thursday he would not rule out direct countermeasures against Japan if Tokyo maintains restrictions on exports of high-tech materials to South Korean companies for an extended period.

"Implementing corresponding measures against Japan cannot be ruled out, because it will take a long time for the World Trade Organization to produce a conclusion," said Finance Minister Hong Nam-ki in a radio broadcast.

Amid a growing dispute over wartime forced labor between Tokyo and Seoul, Japan on Monday announced stricter restrictions on exports of three materials used in South Korean chips and smartphone displays.

The tighter export controls, which took effect Thursday, could slow the export process by several months, hitting South Korean tech giants such as Samsung Electronics Co. SK Hynix Inc. and LG Display.

So far, South Korea has sought to settle the issue of the export curbs through the WTO.

In October, South Korea's top court ruled that Nippon Steel & Sumitomo Metal Corp. must compensate four South Koreans for their forced labor during World War II, a verdict Japan denounced as "unthinkable."

It was reported Tuesday that Japan is considering expanding its export controls to more items bound for South Korea.

Hong added Thursday that if retaliation leads to further retaliation, there will be "unfortunate damage to both Korean and Japanese economies."

South Korea's Trade Minister Yoo Myung-hee said the same day that Japan's revised export restrictions on would pose a "huge threat" to the global economy and disrupt the global supply chain.

Yoo called for the withdrawal of the latest measures, and bilateral talks to discuss the broader issue of export controls, the trade ministry said in a statement.

Also Thursday, Lee Hae-chan, head of South Korea's ruling Democratic Party, said, "This fight is just the beginning, not the end."