Former Taiwanese President Chen Shui-bian has been indicted on new embezzlement charges just weeks after being sentenced to life in prison, and has filed a lawsuit claiming that the U.S. legally controls Taiwan and should release him from detention, officials and a lawyer said Wednesday.

Prosecution spokesman Chen Yun-nan said the new charges issued Tuesday against the jailed former leader accuse him of embezzling $330,000 from official expense funds for his 11 trips overseas as president.

Chen was sentenced to life in prison on Sept. 11 after being found guilty of embezzling $3.15 million during his 2000-08 presidency from a special presidential fund, receiving bribes worth at least $9 million, and laundering some of the money through Swiss bank accounts.

Chen, who has been detained since late 2008, has denied the accusations and called them a political punishment by the current administration.

He has appealed his sentence, and appears to be trying a new strategy to win his release. On Monday, he filed a petition to the U.S. Court of Appeals for the Armed Forces in Washington, D.C., claiming that the U.S. still controls Taiwan because former colonial power Japan never officially transferred the island to another nation after being defeated in World War II, said Roger Lin, general secretary of Formosa National Legal Strategy Association, a pro-independence group in Taiwan.

The petition says Taiwan therefore technically remains under occupation by the Allied powers, led by the United States.

"Military government continues until legally supplanted, and Taiwan today remains under (the U.S.) military government," it says.

Chen claimed he is immune from the Taipei court's ruling because as president he was acting as civil administrator for the U.S. military government, according to the petition, which demands that Washington release him.

The American Institute in Taiwan, the de facto U.S. embassy, has declined to comment on the case. The U.S. is Taiwan's most important strategic partner but it does not assert control over the island.

Hsu Yung-ming, a political scientist at Taipei's Soochow University, said it is highly unlikely the U.S. will intervene in Chen's case and he may be using the U.S. lawsuit to attract attention to maintain his political clout.

"What he fears is that there may be fewer and fewer people caring about his case," Hsu said. "Only by attracting more public attention, positive or negative, can he continue to speak out on various political issues and be influential."

Chen has repeatedly denied wrongdoing and charged that he is being persecuted by the administration of current President Ma Ying-jeou for his anti-China views. Ma, who has been improving ties with Beijing, has denied the accusation.

Taiwan has been claimed by China since the two split amid civil war in 1949, and Beijing has vowed to reassert political control over the self-governing island, by force if need be.

The island was part of China's last dynasty, the Qing, until it was given to Japan in 1895 after the Qing lost a key battle with its eastern neighbor. Japan gave up Taiwan after losing World War II, and it was taken over by China in 1945.

Some Taiwanese activists have long argued that it was never specified which country Japan gave Taiwan to.