China's Defense Ministry said here Wednesday that close-in reconnaissance activities by Japanese planes and ships against China have undermined China's security interests.

Defense Ministry Spokesman Yang Yujun made the remarks at a monthly press conference in response to a question concerning alleged Chinese incursions into Japanese airspace.

Japan's accusations against China are groundless, said Yang, adding that flight activities by Chinese military aircraft operate in accordance with international law and international practice.

In recent years, Japan's Air Self-Defense Force has stepped up China-targeted patrols over the East China Sea, he said.

According to statistics, sorties of Japanese planes conducting reconnaissance activities off the shores of China have increased by 44 percent year-on-year from January to September, he said.

The high-frequency close-in surveillance by Japanese planes and ships has affected China's security interests, severely disturbed China's relevant military training activities and endangered the safety of Chinese aircraft and vessels, Yang said, adding it is the origin of threats to the air, sea and land security of both countries.

He hoped that the Japanese side will take effective measures to avoid and prevent accidents both at sea and in the air.