China is considering designating formal national days of remembrance to commemorate Japan's defeat in World War II and the Nanjing Massacre, state media reported Tuesday, amid bitter disputes over territory and history.

The National People's Congress (NPC) is mulling making September 3 "Victory Day of the Chinese People's War of Resistance Against Japanese Aggression", the official Xinhua news agency said, citing the legislature.

Lawmakers are also considering designating December 13 as a "national memorial day to commemorate those killed by Japanese aggressors during the Nanjing Massacre in the 1930s", Xinhua reported.

In both cases, a "draft decision" will be debated during a bi-monthly session of the NPC Standing Committee from Tuesday until Thursday, Xinhua added.

The rubber-stamp parliament is scheduled to meet next month in full session, but the standing committee has the authority to approve decisions on its own.

The NPC's website did not immediately carry information on the proposal, which comes amid a serious worsening in relations between China and Japan.

At the end of World War II Japan's then emperor Hirohito ordered his country to surrender on August 15, 1945, days after the US dropped atomic bombs on Hiroshima and Nagasaki.

The country formally signed the surrender in a ceremony on the battleship USS Missouri in Tokyo Bay on September 2.

China has traditionally commemorated Japan's defeat the following day, according to past Chinese media reports.

The proposal comes as Beijing and Tokyo are at odds over a group of uninhabited islands in the East China Sea controlled by Japan but claimed by China. Ships and planes from both countries warily eye each other in nearby waters and skies, leading to fears of miscalculation and possible conflict.

- Worsening tensions -

Tensions worsened further in late December when nationalist Japanese Prime Minister Shinzo Abe visited Tokyo's Yasukuni Shrine -- which commemorates Japan's war dead as well as convicted war criminals from World War II.

China and South Korea see the shrine as a reminder of Japan's 20th century aggression and colonialism.

The day to commemorate Japan's defeat "must be set through legislative procedures to reflect the will of the Chinese people and remind us of the need to remember history, cherish peace and create a better future", said Li Shishi, director of the NPC Standing Committee's legislative affairs commission, according to Xinhua.

Japan invaded China in the 1930s and the two countries fought a full-scale war from 1937-1945, part of the broader Second World War.

China says more than 300,000 people died in what has come to be known as the "Rape of Nanjing", a spree of killing, sexual assault and destruction over six weeks after the Japanese military entered the country's then-capital on December 13, 1937.

Though some foreign academics put the number of deaths much lower, no respected mainstream historians dispute that a massacre took place.

China, which says that 20.6 million died as a direct result of Japan's invasion and occupation, has been intensifying criticism of Tokyo in state and Communist Party-controlled media as the territorial and historical disputes worsen.

Japan, which was occupied after its defeat and became a vibrant liberal democracy, has issued apologies for its wartime conduct in Asia.

But frequent statements by conservative politicians and public figures seemingly backstepping from them or calling into question issues of historical fact have increased suspicion of the country's motives.

Willy Lam, a China politics expert at the Chinese University of Hong Kong, said China's leaders are using remembrance and nationalism to portray contemporary Japan as trying to overturn the outcome of World War II and bolster their own legitimacy.

"The Chinese think that the most effective method of criticising Japan is to cast this in the light of history," he said. "The designation of the public holiday means a large-scale mobilisation of Chinese."

"This is going one-step further in the nationalistic campaign" of President Xi Jinping, he added.