Japan Airlines (JAL) and China Eastern Airlines have reached an agreement to expand their codeshare partnership substantially to include their entire China-Japan networks.

Starting on October 8, the airlines will place their respective "JL" and "MU" flight designators on every flight operated by the other, between cities in China and Japan.

The deeper relationship will add Yantai to Japan Airlines' network of 15 Chinese cities, and Shizuoka, Okayama and Nagasaki to China Eastern's existing network of 12 Japanese cities.

According to JAL, the extension of the codeshare to cover the two airlines' entire China-Japan network will make it easier for customers to understand and select more conveniently from the combined operations of both carriers' 386 weekly flights on 42 routes between the two countries.

Apart from the codeshare arrangement between JAL and Shanghai-based China Eastern Airlines, which has been in effect since September 2002, the two carriers have offered reciprocal frequent-flyer program benefits since February 1, 2008.

Members of JAL's frequent flyer program, JAL Mileage Bank (JMB), have been able to earn and redeem award tickets even when flying domestically in China on China Eastern.

Together with its extensive codeshare ties with fellow oneworld Alliance partner Cathay Pacific Airways, which based in Hong Kong, JAL says it is aiming to widen its network coverage to provide business and leisure customers alike with greater convenience and support.