By Ahmed Rasheed

BAGHDAD, Dec 18 (Reuters) Prosecutors who accuse Saddam Hussein of genocide by ordering chemical attacks on Kurds produced documentary evidence at his trial today in a new phase crucial to pinning down his personal responsibility.

Saddam has already been sentenced to death in a separate trial for crimes against humanity in the killing of Shi'ites, but legal analysts have said the prosecution failed to provide hard evidence to prove his criminal responsibility.

In the current case, the former president and six others are on trial for the Anfal -- Spoils of War -- military campaign against ethnic Kurds in northern Iraq in the 1980s in which prosecutors say up to 180,000 people were killed in poison gas attacks and mass executions.

The Anfal trial opened on August 21 and has heard more than 70 witnesses who described chemical air attacks, villages being burned and Kurds being rounded up and tortured.

The witness phase is over, and when the trial resumed today prosecutors turned to the documentary evidence.

They presented a series of documents from Iraq's military intelligence, the president's office and military commanders detailing the chain of command and orders given for the use of chemical weapons.

The first document was a 1987 memo from Iraq's military intelligence seeking permission from the president's office to use mustard gas and the nerve agent sarin against Kurds. It also used the term ''special ammunition'' in what prosecutors said was a reference to chemical weapons.

A second document said in reply that Saddam had ordered military intelligence to study the possibility of a ''sudden strike'' using such weapons against Iranian forces and Kurdish forces. Saddam's defence argues that the Kurdish rebels were siding with Iran, Iraq's enemy in the 1980-1988 war.

An internal memo written by military intelligence confirmed it had received approval from the president's office for a strike using ''special ammunition'' and emphasised that no strike would be launched without first informing the president.

Among several more documents was one from the Army Chief of Staff reporting that an airstrike with special ammunition killed 31 Kurdish fighters and ''communist agents'' and wounded 100 in an area near Dohuk.

The defendants in the case include Saddam's cousin, Ali Hassan al-Majeed, known as ''Chemical Ali''. They have justified Anfal as a legitimate military operation against Kurdish militias who sided with Iran in the war.

Chief prosecutor Munkith al-Faroon said last month he had audio tapes proving the former Iraqi leader personally ordered the gassing of ethnic Kurds in the 1980s.

REUTERS LL HT1905