Chinese fishing boats engaged in "dangerous" maneuvers near a US Navy ship in international waters off China, the Pentagon said, in the latest provocative encounter with American surveillance vessels.

Spokesperson Bryan Whitman said a pair of Chinese vessels last Friday approached the USNS Victorious, which he said was engaged in "routine operations," and forced the US vessel into defensive measures.

"It is unsafe and dangerous behavior and it needs to be addressed" diplomatically, Whitman said.

The US crew, he said, "requested assistance of a nearby Chinese military vessel" prompting the fishing boats to steam away.

"This was clearly well into the international waters, 70 (113 kilometres) off the coast of China."

The latest incident is certain to raise already heightened tensions between the navies of the two major powers as they operate in the South China Sea, the strategic body of water that is home to vital shipping lanes as well as archipelagos believed to sit atop large oil and gas reserves.

Washington and Beijing had already been at odds over high-seas standoffs in early March between Chinese boats and the USNS Victorious as well as another unarmed surveillance vessel, the USNS Impeccable.

Chinese military chiefs believe the Impeccable was on a spying mission, state media has reported, and Beijing has demanded the United States cease what it calls illegal activities in the South China Sea.

The United States keeps a close eye on China's military arsenal, including its expanding fleet of submarines.

The US government said five Chinese fishing boats surrounded and "harassed" the Impeccable on 8 March, prompting US crew to spray a water cannon on the vessels to help avoid a more dangerous clash.

The US immediately protested to Chinese authorities after that encounter, which Washington maintains occurred about 75 miles (120 kilometres) south of Hainan Island in international waters.

Four days earlier in the Yellow Sea, according to the Pentagon, a Chinese fisheries patrol boat shined a high-intensity spotlight on the Victorious, then crossed the US ship's bow in the dark without warning.

Washington responded by dispatching heavily armed destroyers to escort US surveillance ships operating in the South China Sea.

It was not immediately clear if the Victorious was being escorted last Friday in the latest incident.

AFP

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