Lawyers for Saddam Hussein and his seven co-defendants have severed all contact with the court trying the eight men for crimes against humanity after yesterday's second murder of a member of the defence team.
The lawyers said they now considered a second day of hearings in the trial scheduled for 28 November to be 'cancelled and illegitimate'.
They renewed calls on the international community to intervene to stop the trial after yesterday's killing of Adil al-Zubeidi.
Yesterday's killing heightened international concerns about whether the trial can be held in Iraq given the sectarian violence still plaguing the country.
It is not clear what effect a defence boycott would have on the work of tribunal, which retains the power to appoint counsel.
However, it would dent efforts by the Iraqi and US governments to show that the trial is entirely fair.
Elsewhere in Iraq, seven Iraqi policemen have been killed and nine people injured, three of them civilians, in a suicide car bombing in the city of Baquba, about 65km north of Baghdad.
Baquba is the capital of Diyala province which has seen considerable violence linked to sectarian tensions in the run-up to the elections due in the middle of next month.
At the end of October, 30 people were killed and dozens wounded by a suicide bomber who lured customers to a truck laden with dates before detonating a massive charge in a small Shi'ite town near Baquba.
The attack came as US and Iraqi forces announced they had secured the town of Husayba on the Syrian border.
3,500 troops have taken part in Operation Steel Curtain targeting insurgents along the Euphrates valley.
