Emperor Hirohito tonight expressed regret to South Korean President Chun Doo Hwan for the "unfortunate past," his first official comment on Japan's harsh colonial rule of Korea since it ended in 1945.

The statement, delivered at a state dinner at the imperial palace in Tokyo, followed a behind-the-scenes campaign by South Korea to secure something resembling an apology from the emperor, who for many Koreans remains a symbol of the 35-year colonial era.

His words could prove to be the psychological high point of Chun's three-day visit to Japan, which officials in both governments hope will help normalize relations between the two countries, which are historic enemies.

Chun arrived in Tokyo this afternoon amid unprecedented security measures that mobilized an estimated 23,000 police. He is the first Korean head of state to make a state visit to Japan.

"It is indeed regrettable that there was an unfortunate past between us for a period in this century and I believe that it should not be repeated again," Hirohito said before he raised a glass to toast Chun, according to an unofficial translation.

Speaking in a chandeliered banquet hall, the emperor also hailed the role of Korea in Japan's emergence as a nation in the 6th and 7th centuries.

"Many of your people came over to this country . . . and instructed its people in academic learning, culture and technical skills," he said, noting facts of history in which Koreans take pride but which are often ignored in Japan.

In response, Chun told the emperor: "I, on behalf of the entire Korean people, listened solemnly to the remarks your majesty has made on the unfortunate past in the history of our two countries' relations."

In South Korea, however, some people immediately denounced the emperor's statement as insufficient.

"I am not interested in any symbolic or unclear expression," said Song Keun Ho, former managing editor of South Korea's largest daily newspaper, Dong-a Ilbo. "Japan should repent its past mistakes and promise not to repeat history."

Kim Sook Ja, a shopkeeper, said: "Japanese leaders and people are reluctant to apologize directly for their past mistakes. I believe they have never felt sorry for the attack on Pearl Harbor."

But Choo Yeong Sang, spokesman for an association of Korean residents in Japan that is sympathetic to South Korea, said: "He did not use the word apology. But we could fully understand that those were his feelings."

Koichi Kato, a member of the upper house of the Diet, Japan's national legislature, said the emperor's word ikan, translated as "regrettable," is a "very delicate, sophisticated way of apologizing in Japanese culture. I hope that nuance is accurately conveyed."

Before the dinner, Chun and his wife called on the emperor at the palace for 40 minutes. They exchanged photographs and gifts, including a vase and two jewelry boxes.

Chun's remarks were printed and distributed to reporters hours before the dinner. That, and his use of terms very similar to the emperor's, indicated the South Koreans had an advance commitment from Japan that the emperor would express regret, and were told the precise words he would use.

Facing criticism at home for visiting Japan, which many Koreans feel continues to dominate their country economically, Chun had needed an apology to justify his trip.

Japanese officials have cast the visit as an exercise in symbolism that will bring "maturity" to the two countries' relations but will not settle major economic and social issues between them.

In a 90-minute meeting between Chun and Japanese Prime Minister Yasuhiro Nakasone this afternoon, the two leaders limited their discussion to stating their countries' positions on the Korean security situation and other noncontroversial subjects, according to the Japanese Foreign Ministry.

While Japan has no major requests, South Korea has said it wants transfers of Japanese technology, an end to a chronic trade imbalance with Japan and better treatment for the approximately 700,000 Korean nationals who live in Japan.

Large sections of Tokyo were closed off to traffic for the visit today. Policemen stopped cars and trucks for spot checks, an unusual sight in Tokyo, and a police observation blimp circled over the ornate guest house where Chun is staying.

The Korean president had been expected to fly from Haneda Airport to the guest house by helicopter, and four of the craft stood with rotors turning as his plane arrived. But at the last minute, he got into a car and sped into town by a high-speed motorcade using closed-off expressways.

With many of the Korean residents in Japan sympathetic to North Korea, Japanese police have been wary of demonstrations or an assassination attempt. Last year, four of Chun's Cabinet ministers and 13 other South Koreans were killed in a bomb explosion in Rangoon, Burma, that was set up by North Korean agents.

Japanese police reported that about 5,800 leftist students demonstrated in 11 different places to protest Chun's visit. Thirteen were arrested. In addition, an incendiary device destroyed two cars in a Tokyo parking lot, but there was no evidence linking it to the visit.

In South Korea, people lined the streets as the president left for Japan under heavy security. About 500 students demonstrated against his visit and about 30 dissident Christians were arrested for attempting to stage a demonstration.