Japan's foreign minister said Wednesday he had lodged a formal protest over demands by South Korean President Lee Myung-bak that the emperor apologize for wartime atrocities if he wants to visit.

Koichiro Gemba said he could not understand why Lee had made the call, which came as the two countries face off over disputed islands in one of the worst diplomatic spats between the uneasy neighbors for several years.

"It is difficult to comprehend why President Lee made remarks like that yesterday," Gemba told reporters. "It is extremely regrettable."

Lee on Tuesday said Emperor Akihito would have to say sorry for past excesses if he wanted to go to South Korea.

But the comments appeared to have taken Tokyo by surprise.

"Japan has not raised the issue with the South Korean government about the emperor visiting the country," Gemba said.

"When we face difficult issues which we need to handle calmly, any remarks or actions that incite nationalism will not benefit the interests of South Korea," he said, adding Tokyo had lodged a protest through diplomatic routes.

A Japanese television station said Wednesday it was postponing the airing of a South Korean drama series starring an actor who took part in a swim to a group of islands at the center of the territorial row.

BS Nippon Corporation said it would replace A Man Called God, which features popular actor Song Il-kook and was to due air from next week, with a re-run of another South Korean drama series.

"We have decided to change our programming after considering the impact of the main actor swimming to Takeshima," a station spokeswoman said, referring to the isles known as Dokdo in Korean.

A team of South Koreans reached the islands on Wednesday, finishing a 220-kilometer relay swim from the east coast.

In a speech Wednesday to mark the anniversary of the 1945 ending of Japan's 35-year colonization of the Korean peninsula, Lee called on Tokyo to take responsibility for wartime sex slavery it forced on women in occupied countries.

He said Japan was "a close neighbor, a friend that shares basic values, and an important partner that we should work with to open the future".

"However, we have to point out that chain links tangled in the history of Korea-Japan relations are hampering the common march toward a better tomorrow in the Northeast Asian region, as well as bilateral ties," Lee said.

"Particularly, the issue involving mobilization of 'comfort women' by the imperial Japanese military goes beyond relations between Korea and Japan," he said. "It was a breach of women's rights committed during wartime as well as a violation of universal human rights and historic justice. We urge the Japanese government to take responsible measures in this regard."

Tokyo has repeatedly apologized for occupation-era crimes but has consistently rejected South Korea's demands for specific talks on the "comfort women" issue. It insists all outstanding issues were settled in a 1965 accord normalizing relations between the two countries, which also included a financial settlement and maintains it was up to the then military government in Seoul to disburse compensation appropriately.

"The issue of compensation demands between Japan and South Korea, including the issue of comfort women, were covered in that accord," Gemba said.

AFP