TOKYO, Aug 27 (Reuters) - Japanese Prime Minister Shinzo Abe sent a condolence message to a ceremony honouring "martyrs" convicted as war criminals after World War Two, his top spokesman said on Wednesday, news that could snarl efforts to thaw chilly ties with China.
Abe sent the message in April to a Buddhist temple in western Japan housing a monument to more than 1,000 "Showa Martyrs", including wartime leaders convicted by Allied tribunals who were executed or died in prison, an official of a group sponsoring the event told Reuters.
The term "Showa" refers to the late Emperor Hirohito, in whose name Japanese soldiers fought World War Two.
"I offer my sincere condolences to the spirits of those Showa martyrs who gave their lives for the sake of today's peace and prosperity, becoming the foundation of the fatherland," the official quoted Abe as saying in the message.
"I pray for eternal peace and pledge to carve out a path to a future of human coexistence," he added.
The same wartime leaders are enshrined along with war dead at the more widely known Yasukuni Shrine in Tokyo, visits to which by Japanese leaders typically outrage China, where memories of Japan's past militarism run deep.
Abe surged back to power in December 2012 pledging to revive the economy, but remains committed to a conservative agenda that includes recasting Japan's wartime past with a less apologetic tone and easing the limits of its pacifist constitution.
Abe sent the message as the head of the ruling Liberal Democratic Party, Chief Cabinet Secretary Yoshihide Suga told a news conference. "As such, the government thinks of him in this respect as a private citizen," Suga added.
News of the message comes as Abe is reaching out to Beijing in hopes of a summit with Chinese leader Xi Jinping at a gathering of Asia-Pacific leaders in November.
But on Wednesday, China's Foreign Ministry did not immediately respond to a request for a comment.
Ties between Asia's two biggest economies have been frayed by rows over the legacy of Japan's wartime militarism, a territorial feud over tiny islands in the East China Sea, and mutual mistrust over defence policies.
Abe provoked angry criticism from China and South Korea when he sent a ritual offering to Yasukuni Shrine this month, but he stayed away from the shrine, in an apparent effort to dampen diplomatic fallout.
The website of the little-known Buddhist monument in Wakayama in western Japan, where Abe sent his message, refers to those convicted as war criminals as "Showa Martyrs" and says the Allied trials were "victors' revenge".
On Wednesday, Suga repeated the stance of Japan's government, which accepted the verdicts of the tribunal convicting the wartime leaders under the 1952 treaty that formally ended the war.
"It is a fact that (the accused) were judged guilty of crimes against peace by the International Military Tribunal for the Far East," Suga said. "Under the San Francisco Peace Treaty, our country accepts those judgments."
Scholars have pointed out what they see as flaws in the war crimes trials, such as the absence of the crime of conspiracy in international law before 1945 and a failure to charge other key figures, such as leaders of ultra-right groups or industrialists.
Some Japanese regard the trial as providing valid, if imperfect, verdicts, but ultra-conservatives reject them entirely as victors' justice.
Abe was among those publicly critical of the war crimes tribunal before he took office for the first time in 2006. (Reporting by Kiyoshi Takenaka, Linda Sieg and Chris Meyers; Additional reporting by Sui-Lee Wee in Beijing; Editing by Clarence Fernandez)