Japan has cast doubt on the human remains of a man North Korea claimed had died after being kidnapped by its agents.

A Japanese dental expert said the cremated remains probably belonged to a woman who was 20 years older.

	Japan's missing Taken in the 1970s and 1980s Eight Japanese said to be dead Five still alive in North Korea The survivors have children in N Korea Kim Jong-il says he has punished the culprits See also: Profiles of the missing

North Korea handed back the remains after its leader Kim Jong-il admitted its agents abducted 13 Japanese during the 1970s and 1980s.

North Korea said eight of the kidnapped people had died, but family members doubt Pyongyang's version and continue to hope their relatives are alive.

North Korea hoped for a breakthrough in relations with Japan when it admitted to and apologised for the abductions.

The kidnapped people were used to help train North Korean spies in Japanese language and customs.

Five Japanese, the only known survivors, are currently visiting home for the first time in 24 years, but their children remain in North Korea.

Japan is demanding the release of all family members and a convincing explanation from North Korea as a pre-condition to an improvement in relations.

Angry relatives

North Korea's claim that eight abductees had died from natural causes was greeted with anger and disbelief.

Our correspondent in Tokyo, Charles Scanlon, says the families can now point to some hard evidence to back up their doubts.

Only one set of remains was handed over to Japanese investigators. They were supposed to be the ashes of Kaoru Matsuki, whom North Korea said died in a traffic accident in 1996.

North Korea said his grave was destroyed in a flood, but they handed over what it said were his remains. The remains had been cremated twice, making positive DNA analysis virtually impossible.

Japanese police said a jaw fragment studied by a dental professor in fact resembled that of a woman in her sixties.

Kaoru Matsuki's brother is convinced he is still alive. Relatives of the seven others also accuse North Korea of lying.

They do not believe the story that all of the remains were washed away in floods and they say the death certificates look like forgeries.

One couple was reported to have died on the same day - in a gas poisoning accident - just weeks after they smuggled a letter out of the country.

North Korea's official news agency KCNA on Tuesday said Japan's demands over the abduction issue, and its concerns over North Korea's nuclear weapons programme, were threatening to "scuttle the hard-won dialogue" between the two.

KCNA said Japan had broken its promise to work to normalise talks.