Around 70 Japanese lawmakers from both ruling and opposition parties visited the war-linked Yasukuni Shrine in Tokyo during its annual autumn festival on Thursday, a day after Prime Minister Shinzo Abe sent a ritual offering, shunning a visit himself.

Yasukuni, viewed as a symbol of Japan's wartime militarism by neighboring countries, has been a source of diplomatic friction with China and South Korea, both of which suffered Japanese aggression before and during World War II. The Shinto shrine honors convicted war criminals along with millions of war dead.

Seoul expressed "deep concern and disappointment" after the visit by the lawmakers. The group included Yoshihiko Isozaki, senior vice industry minister, Katsunobu Kato, chairman of the ruling Liberal Democratic Party's general council, and LDP Diet affairs chief Hiroshi Moriyama.

Two other senior vice ministers and four parliamentary vice ministers of the Abe Cabinet were also among the group members.

Abe, who is currently visiting Europe, has refrained from paying tribute in person at the shrine in central Tokyo since December 2013. That visit worsened Japan-China ties already frayed over the Tokyo-controlled Senkaku Islands in the East China Sea, which Beijing also claims.

In a sign of thaw in Sino-Japanese ties, Abe is scheduled to hold talks with Chinese President Xi Jinping next week in Beijing.

"When the prime minister resigned after his first stint (as premier between 2006 and 2007), he said it was extremely regrettable that he hadn't visited Yasukuni Shrine. I hope he will cherish that feeling," former health minister Hidehisa Otsuji, who led the group, told reporters.

The group included lawmakers from the LDP, the opposition Japan Innovation Party and the Party of Hope. Japan has a total of around 700 lawmakers in both houses of parliament.

A South Korean Foreign Ministry spokesperson said in a statement that Seoul "expresses deep concern and disappointment over the fact that leaders of the government and the parliament of Japan once again sent offerings to and visited the Yasukuni Shrine, which glorifies Japan's history of colonial rule and war of aggression."

The South Korean government "sternly urges the Japanese political leaders to...contribute to advancing (bilateral) relations in a future-oriented manner by demonstrating through action their humble reflection and sincere remorse for Japan's past wrongdoings based on a correct understanding of history," the spokesperson said.

Wartime history continues to cast a shadow over relations between Tokyo and Seoul despite the two neighbors marking the 20th anniversary of a joint declaration for developing a future-oriented relationship.

Japan colonized the Korean Peninsula from 1910 to 1945.