Updated

Supporters of detained former chess champion Bobby Fischer (search) have urged Japan's prime minister to allow him to go to Iceland to avoid prosecution in the United States, the group said Wednesday.

The Committee to Free Bobby Fischer (search) sent a letter to Prime MinisterJunichiro Koizumi (search) on Monday, arguing that the chess great's U.S. passport was improperly revoked and that Japanese law would allow Fischer's departure for Iceland, which has offered him residency.

Fischer, 61, was detained by Japanese immigration officials in July for attempting to travel with an invalid passport. The United States wants him on charges of violating international sanctions, and he is fighting a Japanese deportation order against him.

A potential break in the case came last week, when Iceland — the site of his landmark World Championship victory in 1972 — offered to give Fischer a residency permit. Iceland officials said Tuesday they had refused a U.S. request to drop the offer.

"I implore you to ... let Bobby Fischer, one of the most famous men of the past century, live out his days in peace and freedom," read the letter, signed by the head of the group, John Bosnitch.

Bosnitch, in an e-mail, said that the group had not received a response from Koizumi as of Wednesday.

The United States was standing by its request that Fischer be sent there to face charges he violated international sanctions against Yugoslavia when he played Boris Spassky in 1992 in a rematch of their 1972 bout in Iceland.

"All we can say is that there is a valid federal warrant for Mr. Fischer's arrest," said U.S. Embassy spokesman Michael Boyle.

It remained unclear what Japan intended to do. Japanese officials have said Fischer could go to a third country only if the United States refuses to take him.

Fischer, who has baffled the public with his reclusiveness and odd behavior, has applied while in detention to marry a Japanese chess official. His fiance, Miyoko Watai, has refused to comment on the marriage plans but said she would like to go to Iceland.

A retired police officer from Iceland, Saemundur Palsson, who has been a friend of Fischer's since 1972, is hoping to leave for Japan soon to bring the chess great and his fiancee to Iceland. Palsson had hoped to leave on Tuesday, but was waiting for Japan's government to say whether Fischer would be allowed to leave.