He was transferred to Iraqi custody as the US prepared to hand over the last American-run prison in the country.
Aziz's family members have said they are worried that he will not be safe under Iraqi control, claiming that there is a thirst for revenge against Saddam-era officials that will compromise his treatment.
Badee Izzat Aref, who is representing the former minister, said that he had been denied access to his client in jail after his official permission was revoked.
"The government prevented me on unreasonable grounds. This is a violation of law," Aref said.
He said authorities told him he could not see his client because Aziz was busy standing trial.
A number of former members of Saddam's administration have been executed since his government was toppled by US-led troops in 2003.
Aziz was the only Christian in Saddam's predominately Sunni Muslim administration, serving as foreign minister and later as deputy prime minister.
He surrendered to US forces a month after the invasion of Iraq began. The US continues to hold eight members of Saddam's government with the acquiensce of the Iraqi government.