China's Foreign Ministry says that new commercial flight routes off China's southeast coast that Taiwan objects to are part of an effort to ease the country's chronic flight delays.

China's Civil Aviation Administration says it will open four new routes from March 5.

Taiwan has complained that one route is too close to a busy area of airspace that it administers, while the other three could affect flights between Taiwan and two of its islands.

Foreign Ministry spokesman Hong Lei said Thursday that the planned routes were a response to noticeable increases in recent years in the numbers of flights on the western side of the Taiwan Strait.

China's heavy air traffic and tight control of airspace by the military have given it the world's worst record for flight delays.