China's ambassador to Britain has invoked Lord Voldemort, the villain of JK Rowling's Harry Potter series, in a diplomatic standoff between Beijing and Tokyo over the Japanese prime minister's visit to a controversial war shrine.

"In the Harry Potter story, the dark wizard Voldemort dies because the seven horcruxes, which contain parts of his soul, have been destroyed," ambassador Liu Xiaoming wrote Wednesday in an op-ed in the Daily Telegraph newspaper.

"If militarism is like the haunting Voldemort of Japan, the Yasukuni Shrine in Tokyo is a kind of horcrux, representing the darkest parts of that nation's soul," he added.

Liu's op-ed comes amid the tensions between China and Japan over Shinzo Abe's visit to the shrine last week.

He became the first Japanese head of government since 2006 to pay respects at Yasukuni, which honours Japan's war dead including 14 indicted Class A war criminals.

Japanese cabinet minister Yoshitaka Shindo followed up with a visit of his own on Wednesday.

Abe said last week that the goal of his shrine visit was "to pledge and determine that never again will people suffer in war", but the site is seen elsewhere as a reminder of Japan's 20th-century aggression against China and other Asian nations.

Chinese foreign ministry spokesman Qin Gang said Monday that Abe was "not welcome" by the Chinese people, and it also provoked vehement condemnation from South Korea and rare criticism by Washington, which has a security alliance with Tokyo.

Beijing has been on a diplomatic offensive over the issue, with Foreign Minister Wang Yi making calls to his counterparts in the US, South Korea, Vietnam, Germany and Russia "to convey his alarm", the state-run China Daily newspaper reported.

Liu's op-ed appears to fit into that effort, and he reminded Britons that the victims of Japan's wartime horrors included their own countrymen, noting a new film that "tells the tragic story of a British PoW tortured by the Japanese in the Second World War".

"China and Britain were wartime allies," Liu wrote. "Our troops fought shoulder to shoulder against Japanese aggressors and made enormous sacrifices."

"Our two countries have a common responsibility to work with the international community to oppose and condemn any words or actions aimed at invalidating the peaceful post-war consensus and challenging international order," he added.