The United States military lawyer acting for David Hicks claims the U-S government is blocking Mr Hicks' attempt to gain British citzenship.
Major Michael Mori, in Melbourne to deliver a lecture, says British officials have failed to gain access to the Australian Guantanamo Bay detainee.
It is believed getting British citizenship would lead to Mr Hicks' release.
Without British citizenship, Major Mori says his client faces the prospect of a manifestly unfair trial before a U-S military commission.
Major Mori says the trial is politically biased and the system is unfair.