Japanese Prime Minister Shinzo Abe said Thursday there is no evidence Japan coerced Asian women into working as sex slaves during the Second World War, backtracking from a landmark 1993 government statement acknowledging that tens of thousands of women were forced into prostitution for the military.

Abe's comments to reporters came as a group of ruling party legislators urged the government to revise the so-called Kono Statement acknowledging that Japan's wartime military sometimes used coercion to recruit women to work in the brothels.

"The fact is, there is no evidence to prove there was coercion," Abe said. "We have to take it from there."

Historians say that up to 200,000 women, mainly from Korea and China, were forced to have sex with Japanese soldiers in brothels run by the military government as so-called comfort women during the war.

Japanese leaders have repeatedly apologized, including former prime minister Junichiro Koizumi, who said in 2001 that he felt sincere remorse over the women's "immeasurable and painful experiences."

Abe's comments were likely to provoke a strong reaction from South Korea and China.

Earlier Thursday in Seoul, South Korean President Roh Moo-hyun urged Japan to be more sincere in addressing its colonial past, as dozens of people rallied outside the Japanese Embassy, lining up dogs' heads on the ground. The demonstration marked the anniversary of a March 1,1919, uprising against Japanese rule, which still stirs deep-rooted bitterness among Koreans.

Each of the dogs' heads had a knife placed in its mouth on pieces of paper with the names of Koreans who allegedly collaborated with Japan during its 1910-45 colonial rule. Protest organizers said the animals had been slaughtered at a restaurant, as dogs are regularly consumed as food in Korea.

In a nationally televised address, Roh said Japan "needs to, above all, show an attitude of respecting the historical truth and acts that support this."

"Instead of trying to beautify or justify its past wrongdoing, [Japan] should show sincerity that is in line with its conscience," he said.

Roh's office said late Thursday that it did not immediately have a direct response to the Japanese leader's remarks. In Beijing, calls to the Chinese Foreign Ministry seeking comment were not immediately returned.

The Kono Statement was issued in 1993 by then-chief cabinet secretary Yohei Kono after incriminating defence documents were discovered showing the military had worked with independent contractors during the war to procure women for the brothels.

The statement has been attacked by right-wing nationalists in Japan, who argue the sex slaves worked willingly for the contractors and were not coerced into servitude by the military.

Despite the official acknowledgment, Japan has rejected most compensation claims by former sex slaves, saying such claims were settled by postwar treaties.

Instead, a fund created in 1995 by the Japanese government but funded by private donations has provided a way for Japan to compensate former sex slaves without offering official government compensation. Many former comfort women have rejected the fund.