Tears in the skin of Japan's P-1 patrol aircraft likely will delay induction of the four planes beyond March, a report by Kyodo agency said.

The P-1, manufactured by Kawasaki Heavy Industries and the country's first domestically developed maritime patrol aircraft, will replace the fleet of at least 90 P-3C Orion turboprop aircraft. Kawasaki also produced the majority of Japan's version of the Orion.

Defense Ministry officials said the tears were found at several spots and ranged from 4-6 inches. Discovery of the tears followed ground tests during which pressure was applied to the aircraft's body, the officials said.

Two P-1 aircraft have been test-flown by the Defense Ministry's Technical Research and Development Institute at Atsugi Air Base in Kanagawa Prefecture. Two more P-1s are being assembled, the Kyodo report said.

The P-1 first flew in September 2007 and the four aircraft were handed over to Japan's Maritime Self-Defense Force in March 2010. Development costs have been estimated at around $3 billion at 2007 costs.

The aircraft, nearly 125-feet long with a 115-foot wingspan, is powered by four IHI Corporation XF7-10 turbofan engines, mounted under the low-slung wings and designed specifically by Ishikawajima-Harima Heavy Industries for the P-1. The engines produce around 13,500 pounds of thrust.

Cruising speed of the P-1 is around 516 mph with a range of nearly 5,000 miles and a service ceiling of 44,200 feet.

Armaments includes up to 20,000 pounds of bombs as well as an assortment of depth charges. Missiles include the AGM-84 Harpoon, ASM-1C and the AGM-65 Maverick.

Comparable aircraft are the BAE Systems Nimrod MRA4, the Boeing P-8 Poseidon, Bombardier Aerospace DHC-8-MPA-D8 and the Ilyushin IL-38.

A delay would come at a politically sensitive time for Japan as it grapples with increasing incursions by Chinese ships and naval aircraft into what it considers its maritime territories.

This week China denied that its South China Sea neighbors had anything to fear from is growing naval strength, including development of two aircraft carriers -- the first for the Chinese. Beijing also heavily criticized statements in a major dense document by Japan's Ministry of Defense.

The document called "Defense of Japan, 2011" describes China's rapid modernization of its military hardware as an attempt to "strengthen its capacity to have its military potential reflected in distant locations."

Beijing's buildup of its maritime power and its defense policy in general continues to be "a concern for the regional and the international community," the document said.

To mark Japan's concern over China, the Ministry of Defense created in the white paper a new section dealing with Beijing's activities specifically in the South China Sea, a report by the Yomiuri Shimbun newspaper said.

The document -- the longest annual defense report at nearly 600 pages -- says Japan fears the territorial disputes between China and its neighbors, in particular the dispute over the Spratly Islands, "will affect peace and security in regional and global society."

The Spratly Islands lie off the southwest coast of the Philippines as well as Brunei and Malaysia. Ownership of the Spratly Islands is the most difficult of all the territorial claims because of the number of claimants, including Vietnam and Taiwan.