WASHINGTON - THE United States has decided to provide heavily armed destroyers to escort US surveillance ships operating in the South China Sea after a tense naval standoff this week, a US official said on Thursday, speaking on condition of anonymity.

The US government has said Chinese boats moved directly in front of the US Navy surveillance vessel Impeccable on Sunday, forcing the ship to take emergency action to avoid a collision.

A day after the incident, the USS Chung-Hoon destroyer accompanied the Impeccable - an unarmed ship designed to track submarines with sonar - in the same area, the official said.

Since Sunday's high-seas standoff, there have been no incidents of harassment from Chinese boats or aircraft, he said.

Chinese military chiefs believe the US Navy ship was on a spying mission, state media reported on Wednesday. The US keeps a close eye on China's military arsenal, including its expanding fleet of submarines.

The episode complicated fragile military relations between the world powers, which had improved after the two held defense talks in Beijing last month.

President Barack Obama on Thursday urged more military dialogue with China to avoid similar incidents after talks with Chinese Foreign Minister Yang Jiechi, the White House said in a statement.

'The president also stressed the importance of raising the level and frequency of the US-China military-to-military dialogue in order to avoid future incidents,' it said.

The US government immediately protested to Chinese authorities after the incident, which occurred about 75 miles (120 kilometres) south of Hainan Island.

Beijing has rejected the US account and demanded the United States cease what it calls illegal activities in the South China Sea. The Chinese maintain the area is part of the country's exclusive economic zone. Washington insists the area is part of international waters and that US ships have a legal right to operate there. -- AFP