Sultan Hashim Ahmad al-Tai, Saddam Hussein's former defence minister, said on Sunday that he had no access to chemical weapons and had received no orders to use them in an operation that killed tens of thousands of Iraqi Kurds.
Also on trial is Saddam's cousin, Ali Hassan al-Majid, also known as "Chemical Ali" for allegedly ordering poison gas attacks against the Kurds.
If convicted, the defendants could be sentenced to death by hanging.
"I did not receive any order asking me to use chemical weapons, but if so I would have implemented it. I did not receive any chemical-related weapons."
Chief Prosecutor Munqith al-Faroon said al-Tai knew about the chemical attack, and showed the court a letter sent by his superiors asking him to use "special ammunition (chemical weapons) against enemy poison."
Al-Tai's lawyer said that his client was only defending his country against Iranian attacks in northern Iraq during the 1980-88 war between the two countries.