The chief prosecutor in Saddam Hussein's trial for genocide against the Kurds presented the most serious evidence to date on Monday, implicating the deposed Iraqi leader directly in chemical attacks against his Kurdish population.

Munqith al-Faroon showed the Iraqi court trying Saddam and six other former regime members about 25 documents, including some presidency letters instructing the army to use "special ammunition" — identified as "mustard gas" — to quell a Kurdish rebellion in 1987.

One of the letters, dated in 1987 and signed by Iraq's military intelligence, asked Saddam's presidential office for permission to strike Kurdish rebels with the "special ammunition," al-Faroon said, reading parts of one of the documents, which was briefly shown in a television clip broadcasting trial proceedings.

"It identifies the special ammunition right here as 'mustard gas'," al-Faroon said, pointing to the gas reference in the letter.

A response letter from Saddam's presidential office said it sanctioned the strike, provided that its "goal is not only to harm the rebels," according to al-Faroon, who insisted that the other target was Kurdish civilians.

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Another 1987 letter, this one by Iraq's air force command addressing the defense ministry, said that "there were 44 strikes carried out by 44 warplanes, using special ammunition on the bases of (Kurdish) agents, except for one village because it was near our ground units," al-Faroon said.

Another 1987 letter to the intelligence headquarters in eastern Iraq sent by one of the intelligence offices in the northern Kurdish area read: "A number of reporters have arrived at Sarglou area to see the result of Iraqi shelling, using chemical weapons. It is likely that the reporters will be sent to the areas that were hit to report the incidents to the international public opinion."

Saddam sat silently watching al-Faroon present his evidence.

But one of his co-defendants, Sabir al-Douri — who headed Iraq's military intelligence during the 1980s — ruled out any connection with the alleged chemical attacks, saying such an offensive was not feasible on the "technical and practical levels."

"I suspect that some of these documents are not authentic," insisted al-Douri, who claimed in previous hearings that the Iranian, not the Iraqi, army attacked the Kurds using chemical weapons.

Saddam and six co-defendants have pleaded innocent to charges of war crimes and crimes against humanity for their alleged roles in the 1987-88 military offensive against the Kurds, codenamed Operation Anfal.

The prosecution estimates that 180,000 Kurds were killed when Saddam's army waged a scorched-earth campaign against Kurdish separatist guerrillas, allegedly destroying hundreds of villages, killing or forcing their residents to flee.

Saddam and one other defendant have pleaded innocent to the additional charge of genocide.

If convicted, all the accused could be condemned to death.

Saddam has already been sentenced to death in a separate trial where he was convicted of ordering the execution of 148 Iraqis, including children, after an attempt to assassinate him in the town of Dujail in 1982.

His lawyers appealed against the other trial's verdict and sentence. The appeal court is expected to rule in early January.

Iraqi officials have suggested that Saddam's prosecution on genocide charges would be halted if the appeals court upholds the death sentence of the first trial.

Iraqi Prime Minister Nouri al-Maliki said Friday he hoped it would only be a matter of days before an appeals court rules on Saddam's death sentence.