The Japanese vessels moved close to the territorial waters of the Dokdo Islands 71 times during the first nine of the year, Yonhap news agency reported.
The tiny group of islands is at the center of a long-running controversy between South Korea and Japan over their ownership.
The vessels were near the "contiguous zone" that extends 24 nautical miles out to sea, revealed data from the South Korean Joint Chiefs of Staff that were provided by Rep. Chung Hee-soo.
The ships didn't enter South Korean territorial waters.
The data said that Japanese patrol boats neared the zone 94 times in 2008, 87 times in 2009 and 95 times in 2010.
South Korean Defense Minister Kim Kwan-jin told a parliamentary committee Friday he will outline South Korea's claims to the islands in clear strong terms in an upcoming "white paper."
A small detachment of South Korean police has been stationed on Dokdo since 1954.
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