TOKYO, July 2 (Xinhua) -- Japan on Tuesday stood by its decision to impose stricter controls on exports of some technology-related products to South Korea amid souring tensions triggered by a wartime labor dispute between Tokyo and Seoul.

According to Japan's top government spokesperson, the move by Tokyo was for reasons of national security and does not run contrary to World Trade Organization rules or the spirit of free trade.

Chief Cabinet Secretary Yoshihide Suga said the tighter export controls were not a retaliatory measure against South Korea, but said that Seoul had failed to show a satisfactory solution to the ongoing wartime labor dispute between both parties.

"South Korea did not show a satisfactory solution over the issue of former workers on the Korean Peninsula before the Group of 20 (G20) summit through Saturday, and we can not help but to say the relationship of trust has been severely damaged," Suga told a press conference on the matter.

He added that as the export controls system is founded on mutual trust, that it would be "difficult" to continue with the current arrangements following moves by South Korea to "deny the friendly and cooperative relationship between Tokyo and Seoul."

The South Korean government, for its part, has slammed the measures, calling them "economic retaliation," according to Japan's public broadcaster NHK.

Under the new restrictions, Japanese manufacturers, from Thursday, will now have to file individual applications for exports to South Korea of substances, including but not limited to, fluorinated polyimide and hydrogen fluoride, that are often used in high-tech products like smartphones, TVs and semiconductors.