TOKYO - NORTH Korea will delay a long-awaited probe into abductions of Japanese citizens, officials said on Friday, as dovish Prime Minister Yasuo Fukuda's sudden resignation set back moves to ease tension.

North Korea told Japan through diplomatic channels that it was holding off on launching an investigation into the fate of Japanese abducted in the 1970s and 1980s to train the regime's spies, Foreign Minister Masahiko Komura said.

'This is very disappointing,' Mr Komura told a news conference.

He said North Korea confirmed it planned to hold the probe but would wait 'until finding out the position of Japan's new government'.

The delay comes just after Pyongyang announced it would stop work on disabling its nuclear complex in protest at a US delay in taking North Korea off a list of state sponsors of terrorism.

Tokyo pressed the United States not to remove North Korea from the list without progress in the abduction row, which strikes a powerful emotional chord in Japan.

Mr Fukuda, 72, is a longtime advocate of improving relations with Pyongyang, an arch-enemy in the eyes of many Japanese.

Taking political risks, Mr Fukuda agreed in June to ease sanctions against impoverished North Korea in return for a new investigation into the abduction issue, which Pyongyang long contended was already resolved.

Mr Fukuda abruptly resigned on Monday after months of low approval ratings and a worsening economy.

Chief Cabinet Secretary Nobutaka Machimura, the government's number two, said the new prime minister would also support the probe by North Korea, which in a surprise move agreed to the participation of Japanese investigators.

'Regardless of the change of the government, this is an important diplomatic issue,' Mr Machimura said.

Mr Fukuda was known to want to follow in the footsteps of his late father Takeo Fukuda, who as premier signed a landmark friendship treaty with China in 1978.

The younger Fukuda played a key role in arranging then prime minister Junichiro Koizumi's landmark visits to Pyongyang in 2002 and 2004.

At the first summit, North Korean leader Kim Jong-Il admitted to the abductions for the first time. He allowed five victims to return but said, to Japan's scepticism, that all the others were dead.

The front-runner to succeed Fukuda is Mr Taro Aso, a former foreign minister known for more hawkish views.

Some analysts wondered if an Aso government would be a throwback to Fukuda's predecessor Shinzo Abe, an outspoken conservative who built his career talking tough on North Korea.

'It could split one of two ways. Aso could come in and take action because his nationalist credentials are unimpeachable,' said Prof Phil Deans, a professor at Temple University's Tokyo campus.

'The alternative is that he would take us back to the position of 'no negotiations, no discussions, we must have this (abduction) issue settled 100 per cent to Japan's liking before we proceed',' he said.

A senior Japanese foreign ministry official, speaking on condition of anonymity, said that Mr Aso would support a Japanese role in the six-nation disarmament talks.

'Aso is often portrayed as more hawkish. But I don't know. He's also very pragmatic,' the official said.

Mr Tsutomu Nishioka, the vice president of a national association lobbying for the kidnapping victims, said he was 'generally reassured' with the candidates to succeed Fukuda.

Mr Nishioka, the dean of the Tokyo Christian Institute, said the abduction victims were 'disheartened' by Mr Fukuda's resignation, which came just as the North Korean probe was expected to start.

'Instead of getting bogged down in domestic politics, we wish he had concentrated on diplomacy,' he said. -- AFP