US had been 'spying on China's most advanced warship'

The US spy plane grounded on Chinese Hainan Island was reportedly collecting information on China's most advanced warship.

An intelligence source has said the plane was flying close to the Russian-made Sovremenny class destroyer.

The EP-3 plane had attempted to fly away after colliding with one of two Chinese jet fighters, the intelligence source said.

The source said the EP-3's attempt to fly away was aborted after the second jet fighter opened fire with its machine gun as a warning.

The source - who had monitored the incident by radar and also listened to cockpit exchanges - said he believed the EP-3 was forced to land by the Chinese fighter plane at an airport on Hainan.

US officials, on the other hand, have said the collision with the Chinese fighter had caused sufficient damage to the US plane for it to issue a mayday signal and make an emergency landing.

It was not the first time that a US surveillance plane such as the EP-3 has tried to collect information on the most advanced fighting ship in the Chinese navy, which poses a major threat to US aircraft carriers with its lethal Sunburn anti-ship missiles.

According to the intelligence source, Taiwan's military radar detected the EP-3 flying in circles in the vicinity of the Sovremenny at a low altitude and at a speed of around 150 mph.

Two Chinese jet fighters taking off from their base in Guangdong Province arrived to intercept and drive away the visitor - but the US Navy plane did not at first show any intention of leaving.

The two jets flew in formation side by side with the EP-3 for some time before one of the planes found it could not fly as slow as the US plane, which is powered by four turboprop engines.

The Chinese jet tried to slow down by making a turn, the source said. The attempt to do so caused the fighter to bump into the US aircraft and then crash into the sea.

The spy plane's crew was trained to destroy the highly sensitive equipment and classified material, US Navy officials said. Like all military personnel carrying classified equipment and documents, the crew of 24 had a "classified destruction plan" for what to do in such an emergency.