TOKYO (AFP) - Senior Chinese military officials have admitted for the first time that a frigate locked its radar on a Japanese destroyer during the two nations' spat over disputed islands, Kyodo News agency reported on Monday.

In one of the more serious incidents in an escalating row over ownership of the islands in the East China Sea, Tokyo said the Chinese vessel effectively had a Japanese ship in its sights earlier this year.

Beijing has consistently denied the allegation and accused Tokyo of hyping the "China threat" in a bid to manipulate world public opinion against its giant neighbour.

But Kyodo News cited unnamed "senior Chinese military officials" saying the weapons targeting had taken place.

The officials, including "flag officers" - those at the rank of admiral - told Kyodo it was an "emergency decision", not a planned action, and was taken by the commander of the frigate, the report said.

The Tokyo-datelined report said the comments were made "recently", but gave no specifics.

The radar incident marked the first time the two nations' navies have locked horns in the increasingly bitter spat over the Tokyo-controlled Senkakus, which China claims as the Diaoyus.

The Chinese officials told Kyodo that on January 30 the frigate and the Japanese destroyer were three km apart in international waters some 110 to 130 km north of the outcrops, the report said.

The commander of the frigate directed his vessel's weapons-targeting radar, based on the Chinese military's rules of engagement, without seeking instructions from the fleet command or navy headquarters, Kyodo cited the Chinese officers as saying.

It was not known if the commander had been reprimanded, Kyodo said.

Tokyo has also charged a Chinese frigate locked its radar on a Japanese helicopter in the middle of January.

China's defence ministry has said in a statement faxed to AFP, that on both occasions the Chinese ship-board radar maintained normal operations and "fire-control radar was not used".

It said "the Japanese side's remarks were against the facts" and Tokyo had "recklessly created tension and misled international public opinion" by making the claim.

"The officials urged Japan to calm the situation by not becoming fixated with the incidents and called on Japan to refrain from disclosing its data proving the radar lock," Kyodo said.

There was no immediate response from the Chinese defence ministry when asked for a comment on Monday's report.