A warship sails in South China Sea during a Chinese navy drill in South China Sea, July 28, 2015. [Photo/CFP]

BEIJING -- China is greatly concerned about the United States' push to "militarize the South China Sea region,"  Defense Ministry Spokesman Yang Yujun said Thursday.

Yang told a monthly press briefing that the recent aircraft "cruise" by U.S. Pacific Command chief Harry Harris over the South China Sea has stoked tensions in the region and increased the risk of unexpected air and maritime accidents.

Yang said that, for a long time, the United States has frequently sent military vessels and aircraft to conduct close surveillance of China in the South China Sea. It has also recently strengthened military allies, beefed up its military presence and carried out joint military drills at very short time intervals in the region.

"These moves by the US make people suspect what it really wants in the region," Yang said.

In response to reports about Pacom Commander Harris' comment on the website of the US Defense Department, Yang said some high-ranking officials and officers of the United States have repeatedly made "irresponsible comments" on the South China Sea over the past few weeks.

He said China is firmly opposed to the act by the US side to ignore facts, deliberately play up the "military threat of China" and provoke troubles between China and its neighbors in the South China Sea.

The Defense Department website quoted Harris as saying China wants to change the status quo in the South China Sea to suit its narrow interests. He also accused China of land reclamation that has destroyed the surrounding underwater environment and island building without meaningful diplomatic efforts toward dispute resolution or arbitration.

Yang said China's development of its islands in the South China Sea is aimed at better performing its international obligations and is conducive to safeguarding navigation security in the region. He said the island development is strictly in line with environmental protection standards and requirements.

Yang pointed out that the United States has failed to say a single word on activities by the Philippines and other countries to carry out large-scale construction projects and military deployment for years on islands they stole from China. He said it is an absolute double-standard for the United States to criticize China's legitimate activities in its own territories.

"We advise the U.S. side to stop making such comments, which are true hypocrisy under a shell of justness," Yang said.

Yang said China has always attached importance to developing military-to-military relations with the United States. He called for relevant people on the U.S. side to be careful with their words and deeds by abiding by commitments to not take sides on sovereignty and territorial issues.

They should do more things that are conducive to the growth of bilateral and military relations and to regional peace and stability, Yang said.