Japan's Prime Minister Yoshihiko Noda Tuesday started a visit to South Korea aimed at smoothing prickly relations, bringing with him a set of historic books seized by his country decades ago.

Noda is returning five volumes of Korean royal archives taken out of the country during Japan's 1910-1945 colonisation, Seoul's presidential office said.

The gesture appeared intended to improve the atmosphere for his summit Wednesday with President Lee Myung-Bak, so that it focuses on cooperation rather than thorny territorial and historical disputes.

"We hope (the return) will encourage cultural relations further and lead to a mature relationship," Chief Cabinet Secretary Osamu Fujimura said in Tokyo.

When Noda took office in late August, South Korea urged his government to "look squarely" at the past -- a reference to disputes that have lingered since World War II ended the era of harsh colonial rule.

Relations improved after Japan's tsunami disaster in March, when South Koreans offered aid and sympathy, but worsened this summer when a territorial row over islets in the Sea of Japan (East Sea) flared up again.

The five volumes were to be handed over Wednesday during the summit. By December Japan is to return the remaining 1,200 volumes of archives from Korea's Joseon dynasty, which ruled from 1392 till the Japanese takeover.

Noda and Lee were expected to discuss proposals for a free trade pact, an exchange programme and efforts to restart six-party talks on North Korea's nuclear programme.

Japan, South Korea and the United States say the North must show it is serious about scrapping its atomic arsenal before the long-stalled talks -- which also group China and Russia -- can resume.

While Tokyo and Seoul see eye-to-eye over Pyongyang, they remain at odds over tiny Seoul-controlled islands known as Dokdo in Korea and Takeshima in Japan.

The decades-old sovereignty dispute made the headlines again in June when flag carrier Korean Air mounted a test flight over them.

Tokyo ordered its public servants to boycott Korean Air for a month. Three conservative Japanese lawmakers who planned a trip near the islands to reassert their country's claim were barred from South Korea in August.

The same month, South Korea lodged a strong protest against Japan's 2011 defence white paper, which describes the islands as Japanese territory.

Seoul also complains that its neighbour's school textbooks distort their shared history. And it wants to discuss compensation for Japan's use of Korean women as military sex slaves during World War II.

Dozens of activists protested Tuesday outside the Japanese embassy in Seoul, demanding Tokyo genuinely apologise for atrocities during the colonial era and drop its claim to the islands.

Despite the disputes, some analysts are upbeat about relations.

Park Ihn-Hwi, professor at the graduate school of international studies at Ewha Woman's University in Seoul, said the return of the royal books would improve public sentiment in Korea.

"I don't think relations have deteriorated this year," he told AFP.

"There is a consensus between the two governments that relations should not be strained further by an ongoing territorial row and other disputes such as textbooks."

Park said the two countries would try to step up cooperation in preparation for any regional emergency sparked by North Korea.