BEIJING - Chinese navy said on Tuesday the so-called Chinese navy vessel having fired on Vietnamese fishing boats in waters off the Xisha Islands was a sheer fabrication.

The so-called firing revealed the ulterior motives of relevant Vietnamese authorities, said an unnamed official with the Chinese navy.

The official said that the truth is that at 10:30 am on March 20, four Vietnamese fishing boats illegally entered and fished in the territorial waters off China's Xisha Islands.

Staff aboard the Chinese patrolling vessel tried repeatedly to persuade and demand the Vietnamese boats to leave by whistle blowing, shouting and handflag guiding, but all failed.

Then the Chinese vessel fired into the sky two warning signal shells, which burned out and extinguished in the air.

There is no such things that Chinese vessel fired with weapons or the Vietnamese boats caught fire, said the official.

The Xisha Islands have been inherent parts of the Chinese territory since ancient times, the official said. But the Vietnamese fishing boats have frequently illegally entered China's territorial waters in recent years.

Last year, at least 303 Vietnamese fishing boats intruded into the territorial waters off China's Xisha Islands. But China never captured any Vietnamese boats out of concerns of maintaining military relations between China and Vietnam, the official said.

It is completely legitimate for Chinese vessels to expel boats that illegally enter China's territorial waters to safeguard the country's territorial sovereignty and marine interests.