He said the May 22 summit with Kim, their second in 20 months, would help break the stalemate in bilateral rapprochement talks stalled by the kidnap and nuclear stand-off.

"I cannot make such a decision unless I have determined that my trip to North Korea will lead to some progress," Koizumi told reporters at his official residence.

The premier added that Japan had informed the United States, China and South Korea of his planned visit to the Stalinist state.

The abduction and nuclear issues will be discussed "in a comprehensive manner," the premier said, reaffirming that a package of solutions to the problems is a precondition to the establishment of diplomatic ties.

A row over North Korea's nuclear program has been deadlocked since October 2002, when Washington said the Stalinist state had broken a 1994 nuclear freeze by launching a secret weapons drive.

The one-day trip will be Koizumi's second visit to Pyongyang, following a landmark summit with Kim in September 2002 at which North Korea admitted its agents had abducted at least 13 Japanese citizens in the 1970s and 1980s.

Tokyo believes scores of its civilians may have been kidnapped during the Cold War and wants a proper investigation.

Only five of the 13 Pyongyang admitted to abducting survived and have now returned home. Tokyo also wants the families of the five still in North Korea to be allowed to settle in Japan with the former abductees.

Japan and North Korea are planning to set up a joint working-level panel to investigate the whereabouts of Japanese citizens abducted by North Korean agents, Kyodo reported, quoting government sources.

At their first summit, Koizumi and Kim agreed that Japan would extend economic aid to the impoverished Stalinist state upon normalisation of their diplomatic relations.

But the abduction issue has stalled the process of rapprochement with the Japanese public seething with anger over North Korea's reluctance to send the abductees' families to Japan and come clean on the other kidnap cases.

Japan's financial aid was meant to answer Pyongyang's demand for an apology and compensation for Japan's colonial rule of the Korean peninsula from 1910 to 1945.

The peninsula was divided in 1945 into the communist North and the capitalist South. Japan normalised ties with the South in 1965 by extending economic aid.

The possibility of a visit by the premier, including a summit with Kim, was raised in two-day talks between Japanese and North Korean officials in Beijing last week, news reports earlier said.

Deputy Foreign Minister Hitoshi Tanaka and the ministry's Asian and Oceanian Affairs Bureau director general Mitoji Yabunaka, Japan's point man on North Korea, went to Beijing earlier this month for talks with North Korean officials on the issue.

North Korea wants to cut a deal with Japan as a way to distance it from US President George W. Bush's tough policy against Pyongyang's nuclear arms ambitions, Keio University professor Masao Okonogi said.

"While China and South Korea have already been soft, it will further loosen the encirclement around the North ahead of the US presidential election in November," the prominent Korean affairs expert said.

For Koizumi, a successful summit would be a plus for his ruling party in the run-up to upper-house elections in July, Okonogi said. "If Koizumi misses the chance now, the abduction issue will be stuck until after the US election."

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