TAIPEI, June 8 (Reuters) - Taiwan activated its defence systems on Thursday after reporting 37 Chinese military aircraft flying into the island's air defence zone, some of which then flew into the western Pacific, in Beijing's latest mass air incursion.

China, which views democratically-governed Taiwan as its own territory, has over the past three years regularly flown its air force into the skies near the island, though not into Taiwan's territorial air space.

Taiwan's defence ministry said that starting from 5 a.m. (2100 GMT) it had detected 37 Chinese air force planes, including J-11 and J-16 fighters as well as nuclear-capable H-6 bombers, flying into the southwestern corner of its air defence identification zone, or ADIZ. The ADIZ is a broader area Taiwan monitors and patrols to give its forces more time to respond to threats.

Some of the Chinese aircraft flew to Taiwan's southeast and crossed into the western Pacific to perform "air surveillance and long distance navigation training", the ministry added in its short statement.

Taiwan sent its own aircraft and ships to keep watch and activated land-based missile systems, it added, using its standard wording for how it responds to such Chinese activities.

China's defence ministry did not immediately respond to a request for comment.

China completed a second phase of joint air patrols with Russia over the Western Pacific on Wednesday, following flights on the previous day over the Sea of Japan and East China Sea, prompting concerns in Japan over national security.

In April, China held war games around Taiwan following a trip to the United States by Taiwan President Tsai Ing-wen.

Taiwan's government rejects China's sovereignty claims and says only the island's people can decide their future.