Major airlines in South Korea are joining smaller local competitors in suspending flight services to Japan amid prolonged tension over Tokyo's trade restrictions on Seoul. 

Korean Air Lines(KAL) announced on Monday that its flight route between Busan and Sapporo will be brought to a temporary halt from September third. The company's planes are currently shuttling between the two cities three times a week. 

An official at South Korea's leading flag carrier said the airline had already been considering suspending the route due to competition-triggered oversupply and decided to act on it following a recent drop in demand. 

Meanwhile, booking rates for Korean Air’s flight services to Japan declined by around three percentage points in July from a year earlier.