China and Japan have marked the 25th anniversary of their shared friendship treaty, but some individual concerns - including chemical weapons apparently left in China by the Japanese during World War II - cropped up during a high-level exchange of visits.

Two items topped the agendas during talks in Beijing and Tokyo Monday: the anniversary of the signing of a peace and friendship treaty between the two Asian giants, and the upcoming six-party talks on North Korea's nuclear weapons program.

In Tokyo, Chinese Foreign Minister Li Zhaoxing confirmed that Beijing planned to host the six-way talks for about three days in late August. According to a Japanese official, Mr. Li made the statement to Japanese Foreign Minister Yoriko Kawaguchi.

In Beijing, Japan's chief cabinet minister, Yasuo Fukuda, said the Japanese government understands that North Korea's nuclear weapons will be the main issue on the table at those talks.

However, he said Japan is also intent on using the talks to raise the issue of Japanese citizens abducted in the 1970s by North Korea. Mr. Fukuda thanked the Chinese for helping make the six-day North Korea talks a reality, and said he thinks he has China's support in raising the abduction issue.

However, in Tokyo, the Chinese foreign minister remained noncommittal when asked by his Japanese counterpart for China to act as a go-between on the abduction issue. All those who are still alive are believed to have returned to Japan. The Japanese government wants the abductees' families to be allowed to leave North Korea as well.

Something of a pall was cast over the otherwise rosy Sino-Japanese relations by chemical weapons that surfaced in northern China last week. China's official Xinhua news agency has charged that the weapons were left behind by occupying Japanese soldiers during World War II, and reported that the weapons had already sickened 36 people.

An editorial in Monday's issue of the official China Daily spoke of Japan's "toxic legacy" and called for Japan to "accept its political, moral and legal obligations" to pay for the safe disposal of the weapons. Mr. Fukuda said the matter is being looked into.

Mr. Fukuda said the Japanese government has sent a team to China's Heilongjiang Province to investigate the weapons. He said Tokyo will wait for verification that the poison is indeed from old Japanese weapons before it decides how to proceed.

In a gesture of goodwill, Foreign Minister Li is expected to announce the relaxation of visa requirements for Japanese citizens visiting China for short periods of time. China has become the second most popular tourist destination for Japanese tourists, after the United States.