Taiwan's Defense Ministry said Wednesday that China could acquire the ability to block the Taiwan Strait and its vicinity as early as 2025, posing a "grave challenge" to the self-governed island's air and sea defense operations.

Defense Minister Chiu Kuo-cheng separately told Taiwan's legislature that military tensions with China are at their worst in over 40 years and that China would be fully capable of mounting an invasion of Taiwan in 2025.

The minister called for the utmost efforts to beef up the island's defense.

Shiyu, or Lion Islet, part of Kinmen County, one of Taiwan's offshore islands, is seen in front of the Chinese city of Xiamen, China, on April 20, 2018 in Kinmen, Taiwan. (Getty/Kyodo)  

The projection about a Chinese blockade of the strait dividing mainland China from Taiwan was made in a report submitted to the legislature at a time when the island's government has seen scores of Chinese warplanes entering its air defense identification zone in recent days.

Chiu made the remarks to a committee reviewing a special budget worth NT$240 billion ($8.6 billion) for producing indigenous weapons including missiles and warships.

The ministry report said China has been making preparations centering on mounting an attack on Taiwan while continuing to expand military activities as well as "gray zone" operations that stop short of an armed attack.

The ministry added that a total of about 380 Chinese warplanes entered the island-designated air defense identification zone last year and that over 600 Chinese military planes have done so this year.

The report also noted that China has two aircraft carriers and has ramped up the production of submarines and destroyers, while accelerating the formation of amphibious assault ships into a unit.