It was the prime minister's fourth visit since he took office

The visit prompted a swift rebuke from China, whose deputy foreign minister expressed "righteous indignation" on behalf of the people of Asia.

It was the fourth such visit by Mr Koizumi since he took office in 2001.

The Yasukuni shrine honours 2.5 million of the country's dead in conflicts since 1853, including a number of war criminals.

These include Japan's wartime Prime Minister Hideki Tojo, who was hanged for war crimes in 1948.

Correspondents say Mr Koizumi's visits are aimed at pleasing the conservative wing of his Liberal Democratic Party.

Visits to the Yasukuni shrine always cause a storm

But they are opposed by China and other Asian countries which Japan invaded and occupied at the beginning of the 20th Century and during World War II.

China summoned the acting Japanese ambassador to make "solemn representations" over Thursday's visit.

Deputy Foreign Minister Wang Yi told Harada Shikahito that it might damage political ties, the Xinhua news agency reported.

"The visit not only goes against Koizumi's own promise to exercise introspection when dealing with the history of aggression," he said. "It also further undermines the political basis of Sino-Japanese ties."

Earlier, responding to questions about possible criticism from Japan's neighbours, Mr Koizumi said: "One does not comment about another country's respect of its history, traditions or customs."

A crowd of New Year revellers were at the shrine when the prime minister arrived, wearing the long pleated trousers of a traditional, formal costume.

He waved at them as they shouted New Year greetings, while he was led up the steps by a Shinto priest in white robes.

Mr Koizumi had earlier attended a ceremony at the Imperial Palace, which adjoins the Yasukuni shrine.