(Adds Chinese Defence Ministry comment)
By Phil Stewart
WASHINGTON, July 20 (Reuters) - China has sent a spy ship to international waters off Hawaii during a giant U.S.-led naval exercise involving 22 countries, even though Beijing is participating in the drills for the first time this year, the U.S. Navy said on Sunday.
The Navy played down any U.S. intelligence risk associated with the proximity of the Chinese surveillance vessel and noted that China also sent a similar ship to monitor the last Rim of the Pacific (RIMPAC) exercise two years ago.
"We've taken all necessary precautions to protect our critical information," said Captain Darryn James, chief spokesman of the U.S. Pacific Fleet.
"We expect this ship will remain outside of U.S. territorial seas and not operate in a manner that disrupts the ongoing Rim of the Pacific maritime exercise."
China's Defence Ministry, in a statement faxed to Reuters, said its naval vessels had the right under international law to operate "in waters outside of other country's territorial waters".
"China respects the rights granted under international law to relevant littoral states, and hopes that relevant countries can respect the legal rights Chinese ships have," it said, without elaborating.
U.S. officials hope China's participation in RIMPAC helps avert misunderstandings on the high seas but analysts long cautioned the maneuvers may ultimately help Beijing strengthen its growing naval capability by observing the forces of the United States and its allies.
Still, the United States also conducts surveillance operations in international waters and airspace and the Navy did not voice protest over the appearance of the Chinese vessel, described as a Chinese Navy auxiliary general intelligence ship.
Even though the vessel was inside America's 200-nautical mile exclusive economic zone, it was operating within international law, James said.
Still, James said he was unaware of any participant doing something similar since the drills began in 1971.
"To my knowledge, this is the first time a nation has ever sent a surveillance ship near Hawaii while also having invited ships participating in the RIMPAC exercise," James said.
The Chinese ships participating in the drills are missile destroyer Haikou, missile frigate Yueyang, supply ship Qiandaohu and hospital ship Peace Ark.
Chinese forces include two helicopters, a commando unit and a diving unit, a total 1,100 personnel.
The exercises come at a time when tensions are high between Beijing and U.S. allies such as Japan and the Philippines over China's pressing of territorial claims in the South and East China Seas.
They also come after a dispute between China and Vietnam that led to one of the worst breakdowns in ties since they fought a brief war in 1979. (Additional reporting by Ben Blanchard in Beijing; Editing by Lisa Shumaker and Alan Raybould)