The Japanese government will submit a bill this year to allow women to ascend the imperial throne for the first time in centuries, Prime Minister Junichiro Koizumi said Friday in a speech to Parliament.

Koizumi did not provide details of the bill or when it would be submitted, but he said the proposal would be in line with the findings of a high-level panel, which has recommended letting female heirs assume the Chrysanthemum Throne.

Japan's imperial family has not produced a male heir since the 1960s, and public opinion is strongly in favor of changing a 1947 law to allow Crown Prince Naruhito's 4-year-old daughter Aiko to become a reigning empress. Aiko is his only child.

"In order that the imperial throne be continued into the future in a stable manner, the government will submit a bill to reform the Imperial Household Law," Koizumi said in what could be his last annual policy speech to Parliament. He has said he will step down when his term ends in September.

In the speech, Koizumi also said Japan will push ahead with wide-ranging reforms which include privatizing the nation's sprawling postal system, reducing the number of public servants and trimming the national budget. He called for more debate on changing Japan's pacifist constitution and strengthening ties with China and South Korea.

Relations with the countries have been strained by Koizumi's visits to a war shrine that China and South Korea say glorifies Japan's militaristic past. Japan and China have also clashed over exploitation of maritime resources, territorial claims and China's recent military buildup.

"While there may be differences in opinion or disputes in certain areas, China and South Korea are very important neighbors," Koizumi said. "We will strengthen cooperation from a comprehensive standpoint to construct future-oriented relations based on trust."

Under the 1947 Imperial Household Law, only males who have emperors on their father's side can succeed to the Chrysanthemum Throne. Eight empresses have ruled Japan in the last 1,500 years, the most recent being Gosakuramachi, who was in power from 1762 to 1770.

The idea of allowing female succession has gained strength in recent years as the imperial family, which is deeply respected in Japan, has faced the growing possibility of succession crisis. As Akihito's eldest son, Naruhito is next in line to the throne. But he and Crown Princess Masako have not had a son; neither have Naruhito's younger brother Prince Akishino and his wife Princess Kiko.

The prospects of a male heir emerging dimmed even further when Masako dropped out of public view two years ago because of a nervous illness. Masako, 42, has appeared in public only sporadically since then, and skips many imperial events.

A poll last year by the nationwide newspaper Asahi showed 78 percent of the respondents were in favor of a reigning empress. But the proposal still has opposition in Japan's tradition-bound imperial circles. Prince Tomohito, a cousin of Emperor Akihito, has suggested employing concubines to produce male heirs, as was once done.

The prince, who is fifth in line to the throne, also suggested emperors be allowed to adopt sons and the aristocracy — disbanded after World War II — be revived to create a larger pool of marriage partners and potential heirs.

Those ideas, however, are not being taken seriously by the public and harken to an era far in the past.

Though the late Emperor Hirohito resisted pressure to take a concubine himself, both his father, Emperor Taisho, and his grandfather, Emperor Meiji, were the sons of concubines. Akihito is Hirohito's only son.

Under the recommendations of an independent panel late last year, the law would be changed to give the emperor's first-born child of either sex the right to head the monarchy.