Japan's prime minister is under fire over allegations that he injected politics into the imperial palace by using his clout to arrange a last-minute audience between Emperor Akihito and China's vice president.

The furor over the 20-minute meet-and-greet Tuesday touches on an emotion-laden post-World War II taboo barring the emperor _ who since 1945 has been a ceremonial head of state _ from wielding political power or being used by politicians for their own partisan goals.

The critics are fuming over allegations that Japan's new government bent normal rules requiring a month's notice for imperial audiences and pressured the palace into hastily arranging the meeting between Akihito and China's Vice President Xi Jinping, a rising star in China's leadership, to curry favor with Beijing.

Prime Minister Yukio Hatoyama, who took office in September, has stressed that he intends to improve Tokyo's ties with China. Last week, more than 100 lawmakers from Hatoyama's progressive Democratic Party met Chinese Communist Party leader Hu Jintao in the Chinese capital.

Hatoyama's political opponents say that the imperial audience was arranged to return the favor.

Since the end of World War II, Japan's emperor has had a tightly restricted role and is generally kept away from exerting political influence. A symbolic figurehead, he rarely speaks in public, does not set his own schedule and his infrequent foreign trips must be approved by the Cabinet.

The changes in Akihito's imperial role _ imposed by the U.S.-led Allies after Japan's surrender ended the war _ have good reason.

Before and during World War II, Japan's emperors were often used as political pawns to rally the nation behind its colonial expansion across Asia. The late Emperor Hirohito, Akihito's father, was revered as a living god and Japan's troops died fighting in his name.

It is not unusual for Akihito to grant audiences to foreign dignitaries.

The meetings, such as one recently held with President Barack Obama, are carefully orchestrated and planned well in advance to avoid hints of favoritism or the appearance of political undertones. The uproar in some quarters in the United States over Obama's low bow underscore that the scrutiny otherwise innocuous imperial audiences can invite.

China's Foreign Ministry spokeswoman, Jiang Yu, said Beijing was pleased by the trip.

"The Japanese side made very considerate arrangements for the visit," she said. "We attach great importance to that."

But the government's last-minute decision to have Akihito meet Xi was seen by many as crossing the line in an attempt by the new administration to score a diplomatic coup.