Japan has approved shipments of a high-tech material to South Korea for the second time since imposing export curbs last month, two sources said, ahead of talks by government officials this week to resolve a dispute stemming from their wartime past.

Relations between the two US allies worsened late last year when a South Korean court ordered Japanese companies to compensate some of their former laborers forced by the firms to work during World War II.

In early July, Japan tightened controls on shipments to South Korea of three materials used in chips and displays, threatening to disrupt the global tech supply chain. Japan also announced a plan to remove South Korea's fast-track export status from later this month.

The material cleared for Japan's exports to Samsung Electronics Co Ltd in South Korea is photoresists, which are crucial for the tech giant's advanced contract chip-making production, the people who were familiar with the matter said on Tuesday.

A Samsung Electronics spokeswoman and a South Korean trade ministry spokeswoman declined to comment. A Japanese official in charge of the issue was not available for comment.

An official at South Korea's presidential office confirmed the exports at a briefing, but said that "uncertainties" will remain until Japan completely removes the tighter export controls it has instituted.

"Tokyo's latest export approval is positive for the local industry, but I don't see Japan's move as a conciliatory message to South Korea," another South Korean government official told Reuters, requesting anonymity because of the sensitivity of the matter.

Earlier this month, Japan gave the green light to the export of photoresists to Samsung Electronics for the first time since it imposed the restrictions.

Samsung Electronics shares ended up 1.95 percent on Tuesday, leading the wider market's gain of 1.05 percent.