China condemned the US Pacific air force commander Monday for "irresponsible remarks" after he warned it would be provocative if Beijing declared an air defence zone over the South China Sea.

The response ratchets up a war of words also involving the Philippines and Japan over territorial disputes in the South and East China Seas respectively.

Beijing set up an "air defence identification zone" (ADIZ) over the latter waters in November that included contested islands claimed by it and Tokyo, prompting condemnation by Washington.

Amid concerns Beijing may do the same to assert territorial claims in the South China Sea, US Pacific Air Force Commander Herbert Carlisle said on Sunday such a step would be "very provocative".

At a regular press briefing on Monday, China's foreign ministry spokeswoman Hua Chunying hit back, saying that "setting up an air defence identification zone is a reasonable right for any sovereign state to exercise.

"Relevant officials should reflect carefully on what standing they have to make any irresponsible remarks about China's exercising its own reasonable and legitimate rights."

Pointing out that the US and other countries also have ADIZs, she asked, "Why can only China not (do the same)?"

"We hope that relevant countries and officials can stop making irresponsible comments," she said.

Beijing requires aircraft flying through its ADIZ to identify themselves and maintain communication with Chinese authorities, but the zone is not a claim of sovereignty.

Carlisle also criticised recent actions by Manila and in particular Tokyo, saying that many countries needed to act to de-escalate tensions.

"Some of the things, in particular that have been done by Japan, they need to think hard about what is provocative to other nations," he said in an interview in Singapore with the US news agency Bloomberg.

Last week Philippine President Benigno Aquino compared China's efforts to seize disputed territories to Nazi Germany's actions before World War II, and urged world leaders not to repeat the mistake of appeasement -- comments Chinese foreign ministry spokesman Hong Lei dismissed as "unreasonable".

Meanwhile China and Japan have slammed one another over disputed islands, as well as Beijing's grievances over Japan's history of imperial aggression until its defeat in 1945.

Tensions spiked even further after Japan's nationalistic Prime Minister Shinzo Abe in December visited the Yasukuni shrine, which commemorates Japan's war dead, including a handful of war criminals executed at the end of World War II.

In opinion pieces in January, both countries' ambassadors to the UK invoked the fictional evil wizard of the Harry Potter series, Voldemort, in accusing the other side of escalating the conflict.

On Friday Beijing had denounced a US official's call for China to clarify or adjust its claims in the South China Sea, calling the remarks "irresponsible".

Beijing claims the sea almost in its entirety, even areas a long way from its shoreline, but portions are also claimed by the Philippines, Vietnam, Malaysia, Brunei and Taiwan.

China condemns Japanese city's kamikaze letter plan
Beijing (AFP) Feb 10, 2014 - China expressed outrage Monday at a proposal by a Japanese city to list letters written by World War II suicide pilots on a United Nations register -- alongside Anne Frank's diary.

Minami-Kyushu last week filed an application to include the Japanese kamikaze pilots' farewell letters on a Unesco world memory list, media including public broadcaster NHK have reported.

The museum wants to win registration in 2015, "to forever hand down the letters to generations to come as a treasure of human life", it says on its website.

Among documents on the Unesco register is the diary of Anne Frank, written by the Jewish girl who hid in Amsterdam with her family in an attempt to avoid Nazi deportation. She died at the Bergen-Belsen concentration camp in Germany in 1945.

"This is an effort to beautify Japan's history of militaristic aggression, and challenge the victory of the World Anti-Fascist War and the postwar international order," Chinese foreign ministry spokeswoman Hua Chunying said when asked about the letters.

Speaking at a regular press briefing, she added that Japan committed "numerous" crimes against humanity during World War II.

"This effort runs completely counter to UNESCO's objective of upholding world peace, and will inevitably meet strong condemnation and resolute opposition from the international community," she said.

Relations between Beijing and Tokyo are heavily coloured by history, particularly the rampage across China by Japan's imperial forces in the 1930s and 1940s, when Chinese government researchers say 20.6 million people were killed.

Tensions have escalated amid a heightened row over disputed islands controlled by Japan but claimed by China and the visit in December by Japanese Prime Minister Shinzo Abe to a Tokyo shrine commemorating Japan's war dead, including 14 senior officials convicted of war crimes after World War II.

The kamikaze letters are included in thousands of items kept at the Chiran Peace Museum in Minami-Kyushu, left behind by 1,036 pilots who died in suicidal attacks on enemies in the final years of World War II.

The small town of Chiran is known as the place from which kamikaze planes would depart on their flight of no return.

Unesco's Memory of the World Programme was established in 1992 to preserve global documentary heritage.