Toppled former Iraqi President Saddam Hussein will challenge the legality of the special tribunal, due to open inside Baghdad's fortified Green Zone on October 19, a London-based member of his legal team told the BBC.

"He had full immunity under the prevailing Iraqi constitution and you cannot have a retroactive legislation that removes that immunity," Lawyer Abdel Haq Alani said in an interview with the BBC's "Newsnight" programme on Thursday.

Iraqi officials say the only charge against Saddam so far is the killing of more than 140 men in the mostly Shi'ite village of Dujail after a failed 1982 assassination attempt against him.

Alani said the defence will argue that those killed had been "tried and found guilty and sentenced to death according to the Iraqi criminal code," and Saddam's only role was to sign their death warrants.

Alani, who told Reuters in September that Saddam had been denied his legal rights, said he still thought the former Iraqi president would not have a fair trial.

The BBC said Saddam's defence team has just received an 800-page bundle outlining the prosecution case.

The report said many of the pages they have been sent are unreadable and they still have no charge details.

Saddam has been held by U.S. forces since they captured him in 2003. He sacked his defence team in August to bring in a more professional group.

Alani, an Iraqi born barrister, has assembled a legal team with Khalil Dulaimi, who is based in Baghdad and is the only lawyer who has so far been allowed to meet Saddam.

British lawyer Anthony Scrivener, who has been involved in some of Britain's most high profile trials, has agreed to join the team to help defend Saddam, according to the BBC.