KUALA LUMPUR, Malaysia (AP) - Vowing to push North Korea to give up its nuclear weapons program and end an emotional tug-of-war over the fate of five Japanese citizens abducted decades ago, Japanese officials said Monday the "hurdle is very high" as both countries begin talks to establish diplomatic relations.

The talks, made possible by an unprecedented summit between the leaders of the two nations last month, mark a major breakthrough in relations between the closed communist state and its former colonial ruler.

The head of Japan's delegation, Katsunari Suzuki, acknowledged Monday the two-day talks that begin Tuesday in Malaysia will be difficult.

"The hurdle is very high," Suzuki said. "But we will do our utmost to take advantage of this door opened by the prime minister."

Tokyo refuses to normalize relations until the abduction and nuclear weapons issues are resolved.

"We hope to make appreciable progress," Suzuki said.

The top priority for Japan, he said, is the permanent return of five Japanese kidnapped by North Korean spies in 1978. Tokyo also wants North Korea to allow repatriation of the children of the five abductees.

The five are the only survivors of 13 confirmed abduction cases and are in Japan for their first homecoming, though they had to leave their seven children behind. The visit has become an emotional tug-of-war. North Korea had originally only intended for them to stay for a week or two, but Japan last week said they would remain indefinitely.

Agreement also was not likely on Japan's demand that North Korea give up its nuclear weapons program.

Japanese Prime Minister Junichiro Koizumi won a major political coup when North Korean leader Kim Jong Il reversed years of denials and acknowledged his country's agents had abducted Japanese in the late 1970s and early '80s. The abductees were used to train North Korean spies in Japanese language and culture, officials say.

Kim's confession opened the way for this week's talks, but normalizing relations appears to be a distant.

A similar round of talks broke down two years ago when North Korean delegates stormed out after angrily denying the abduction allegations. And the initial joy over the homecoming of the abductees has been replaced by a public backlash over news that at least eight others died.

Heightened international tensions over North Korea's recently revealed nuclear weapons program also put Japan in a delicate position, and threatened to once again derail the talks.

Koizumi said Monday the Kuala Lumpur talks will have a "great impact on peace and stability" in the region.

"We intend to make the talks comprehensive," he said in a speech at the Asian-Pacific Economic Cooperation forum in Mexico. "We will discuss the abduction issue and security, as well as problems of the past, the present, and the future."

Relatives of the abductees held a news conference in Tokyo Monday to seek hard bargaining for the survivors' permanent return.

Japan has joined the United States and South Korea in demanding that North Korea abandon its nuclear weapons program "in a prompt and verifiable manner." Japan was also expected to demand compensation from North Korea for the abductions and damage caused to Japanese Coast Guard vessels in a gunbattle last year with an alleged North Korean spy ship.

North Korea, which has recently shown signs of opening to the outside world in an attempt to win economic aid, will likely focus on compensation for Japan's 1910-45 colonization of the Korean Peninsula.

Japan, which cut off aid to the North two years ago, has balked at that. But at last month's summit, Koizumi apologized for the occupation and pledged an unspecified amount of economic aid for the North once relations are established.