Korean Air will suspend its flights between the South Korean city of Busan and Japan’s Sapporo from September amid the deepening diplomatic and economic row between the two countries, local media reported on Monday.

According to South Korean media outlets, the airline plans to suspend flights from 3 September.

Meanwhile, Japan’s Jiji press agency reported that South Korean low-cost airline T’way Air would also suspend regular flights from South Korea to three airports on Japan’s Kyushu island.

Tensions began on 1 July when Japan announced restrictions on exports of three chemical materials to South Korea — fluorinated polyimides, photoresist and hydrogen fluoride — that are vital to the production of semiconductors and displays.

The Busan city administration has said earlier that it will stop exchange programs with Japan over the worsening relationship.

Japan’s export curbs have widely been seen as a response to a series of South Korean court rulings that have obligated a number of Japanese firms to pay reparations to former Korean workers who were forced into labour during World War II by Japan, a colonial power at the time.

Japan’s official position regarding the reparations is that the bilateral 1965 Treaty on Basic Relations had fully resolved the matter, meaning that, from Tokyo’s point of view, the court rulings go against previous bilateral agreements.

Japan ruled over the Korean Peninsula, then its colony, from 1910 to 1945. In 2005, the two countries reached a deal with South Korea agreeing to make no further compensation demands, either at the government or individual level, after receiving $800 million from Japan as restitution for its colonial rule.