Lee Jin-man, Associated Press
Chinese President Xi Jinping, left, and first lady Peng Liyuan wave following their visit to South Korea at Seoul Military Airport in Seongnam, South Korea, Friday, July 4, 2014. Xi highlighted Japan's brutality against China and South Korea in the last century during a speech on the final day of his visit to Seoul on Friday amid worries in both countries about recent nationalism in Tokyo.

SEOUL, South Korea — The leaders of China and South Korea expressed concern Friday about Japan's recent reinterpretation of its war-renouncing constitution and its re-examination of a past apology for wartime atrocities, a South Korean official said.

Japan colonized the Korean Peninsula and occupied parts of China, often brutally, before and during World War II. Many people in China and South Korea still harbor a strong resentment against Japan, and there are concerns in both countries about growing nationalism in Tokyo.

Visiting Chinese President Xi Jinping and his South Korean President Park Geun-hye had "lots of discussions" about Japan, and shared worries about its "revisionist attitude" and reinterpretation of its constitution to allow its military a larger international role, senior South Korean presidential official Ju Chul-ki told reporters.

Both leaders also regretted Japan's recent review of its landmark 1993 apology for forcing Asian women into wartime prostitution because it was an apparent attempt to "disparage" the apology, Ju said, according to the presidential Blue House.

Last month, a Japanese panel confirmed the validity of a study that led to the apology, but South Korea called the review unnecessary and said it included material that undermined the reliability of the apology.

Historians say up to 200,000 women from across Asia, many of them Koreans, were forced to provide sex to Japan's front-line soldiers. Japanese nationalists contend that the so-called "comfort women" were voluntary prostitutes, not sex slaves, and that Japan has been unfairly criticized for a practice they say is common in any country at war.

Earlier Friday, Xi highlighted Japan's past brutality against China and Korea during a speech on the final day of his visit to Seoul.

"Our two countries had big suffering when (Japan) launched barbarous aggression on China and Korea and annexed and occupied the Korean Peninsula in the first half of the 20th century," he said.

He noted that in the late 16th century a Chinese dynasty sent troops to help a Korean dynasty defeat invading Japanese troops.

"Both countries' nationals ... walked shoulder to shoulder to battle grounds together 400 years ago," Xi said, speaking through an interpreter.

China assisted North Korea and fought against South Korea during the 1950-53 Korean War, while American-led U.N. troops fought alongside South Korea.

South Korea and China established diplomatic relations in 1992. The countries now have booming trade ties and share concerns about Japan's military ambitions and what critics see as recent attempts by Tokyo to obscure its bloody past.