Three people were dead and five missing Friday in a fishing boat fire in waters near islands at the centre of a dispute between Tokyo and Beijing, Japan's coastguard said.

"We have been informed by South Korean officials that three people died and five are missing from a South Korean fisheries ship that caught fire in waters near Uotsuri island," a spokesman said, referring to an island in the East China Sea.

A coastguard patrol plane "discovered part of a boat that is believed to be the South Korean vessel at 8:24 am (2324 GMT)," the Japanese coastguard said in a statement, adding it was continuing the search for the missing crew members.

The incident was first discovered by a South Korean vessel in waters some 100 nautical miles north of Uotsuri, the largest island in the Tokyo-controlled Senkaku chain, claimed by Beijing as the Diaoyus.

The coastguard said the ship had nine crew members aboard, comprising seven South Koreans and two Chinese, it said.

The other South Korean vessel had recovered four of the nine crew, of whom three were already dead, it said.

The Japanese coastguard, after receiving the initial report from South Korea's coastguard, sent a patrol plane and two patrol boats to the area.

"We don't know yet the nationality of the dead and missing," the spokesman said.

The maritime dispute between Tokyo and Beijing, which has simmered for years, hotted up last year when the Japanese government nationalised some of the islands, triggering anger and demonstrations in China.

Observers said the protests had some backing from communist authorities in Beijing, who use nationalism to bolster their claims to legitimacy.

Tokyo's defence ministry has said F-15s were sent airborne to head off Chinese state-owned -- but not military -- planes four times in December, including one occasion when Japanese airspace was breached.

They were also mobilised in January, it said.

Tokyo is embroiled in a separate row with Seoul over a different set of islets, with tensions flaring last summer after South Korean President Lee Myung-Bak paid a sudden visit to the disputed territory.