By Kiyoshi Takenaka

TOKYO (Reuters) - Japan's defense planners are seeking its biggest budget ever for the coming fiscal year, including a bulk order of patrol planes and a stealthier submarine, as Prime Minister Shinzo Abe bolsters the military in the face of a territorial spat with China and North Korea's nuclear program.

The Defense Ministry on Friday requested a 3.5 percent increase to 5.05 trillion yen ($48.7 billion) for the year starting next April. If approved, this third increase in a row will more than reverse the decade of cuts that Abe ended after coming to office in December 2012.

The hawkish premier, taking a more assertive stance on national security, has also ended a ban on Japanese soldiers fighting abroad and eased curbs on weapons exports.

By testing the constraints of Japan's pacifist postwar Constitution, Abe has angered some neighbors, especially Beijing, which accuses him of reviving the nation's wartime militarism.

Japan, in turn, is wary of the rapid military buildup in China, which has overtaken Japan in recent years as the world's second-biggest economy. Beijing's military budget has jumped fourfold over the past decade to 808 billion yuan ($132 billion), nearly triple Japan's.

(1 US dollar = 103.6900 Japanese yen)

(1 US dollar = 6.1423 Chinese yuan)

(Additional reporting by Tim Kelly; Editing by William Mallard)