The Mainichi Daily News said Masako Suzuki, Fischer's attorney, told a news conference in Tokyo the former world chess champion is probably being persecuted for his political views.
Fischer remains in an immigration bureau detention center after his arrest at Narita Airport last month for trying to travel with a passport U.S. authorities said is invalid.
In a handwritten statement, Fischer claimed to be a victim of "the filthy U.S. government and the filthy U.S.-controlled Japanese government working in collusion and in a criminal conspiracy."
Fischer said: "I no longer wish to be an American citizen. Enough is Enough."
Fischer's lawyer said she had applied to the U.N. High Commissioner for Refugees to register the former chess champion as a refugee. Fischer had already applied for refugee status in Japan.
Fischer has been wanted in the U.S. since 1992 when he ignored U.S. sanctions to play a chess match in Yugoslavia.