Taiwan's defense ministry says 30 Chinese military aircraft entered its air defense identification zone, or ADIZ, on Monday.

The ministry said five types of fighter jets, including the J-16 and the Su-35, and early warning and electronic warfare aircraft were among the planes that entered the southwestern part of the zone.

Officials said most of the aircraft flew over an area close to the Pratas Islands in the South China Sea, which are effectively controlled by Taiwan.

This was the second-largest number of Chinese military planes to enter the zone in a single day this year. The total number of entries so far this year is about 1.5 times the figure logged in the same period last year.

The Taiwanese defense ministry described what it calls "gray zone" threats by China in a report it released in November.

The report says China is trying to take control of Taiwan by wearing down its military capabilities and creating unrest among the people without conducting an armed attack. It suggests that sending aircraft into Taiwan's ADIZ is one of the tactics China is using to achieve that.