China must retaliate for Japan PM shrine visit: media

China's state media today urged "excessive" counter-measures after Japanese Prime Minister Shinzo Abe's inflammatory war shrine visit, as analysts warned against the dangers of provoking smouldering regional resentments.

The comment came after China summoned Tokyo's ambassador yesterday to deliver a "strong reprimand" after Abe paid respects at the Yasukuni shrine earlier in the day.

The site honours several high-level officials executed for war crimes after World War II, a reminder of Japan's 20th century aggression and a source of bitterness for China and other Asian countries.

South Korea, which also has a litany of historical resentments against Japan, slammed Abe's visit as "anachronistic behaviour." And the United States -- Tokyo's key security ally -- issued a rare criticism, saying it was "disappointed" over an act "that will exacerbate tensions with Japan's neighbours".

The Global Times, a paper that is close to China's ruling Communist Party and often strikes a nationalist tone, said that people were "getting tired of... Futile 'strong condemnations'".

"China needs to take appropriate, even slightly excessive countermeasures" or else "be seen as a 'paper tiger'", it warned in an editorial.

It suggested barring high-profile Japanese politicians and other officials who went to the shrine from visiting China for five years.

The visit sparked protests today in both Seoul and Hong Kong, the former British colony which was occupied by the Japanese during the Second World War.

In Seoul demonstrators, most of whom were in their 60s and 70s, shouted anti-Japanese slogans such as "Down with Abe!" and "Boycott Japanese goods!" outside the country's embassy.

Brief scuffles erupted when police tried to stop the burning of Japanese flags but there were no injuries or arrests.

Similar scenes broke out in Hong Kong where protestors burned Japanese military flags emblazoned with the Chinese words for "shame", a picture of Japanese Second World War general Hideki Tojo and a portrait of Abe.

Analysts said the visit showed Abe's determination to drag Japan, constrained by a US-imposed "pacifist" constitution that he wants to change, to the right and nudges Northeast Asia a significant step closer to conflict.

China and Japan, the world's second- and third-largest economies, have important trading ties.

But tensions over East China Sea islands known as Diaoyu in China and Senkaku in Japan have soured diplomatic relations since last year.

Chinese protesters took to the streets in major cities at that time, attacking Japanese diplomatic facilities and businesses, harassing individual Japanese and turning over vehicles made by Japanese manufacturers in demonstrations initially condoned by authorities, eventually restricted.