The United States military announced yesterday that it was bringing death penalty charges against Khalid Sheikh Mohammed and five other men suspected of orchestrating the September 11 attacks, and intended to try them under the Bush administration's much-criticised military tribunal system, which is subject only to partial oversight by the civilian appeals system.

The decision to use Mohammed and the others as guinea-pigs in a constitutionally dubious legal proceeding is likely to trigger a firestorm of anti-American sentiment in the Islamic world and spark a fractious domestic debate in an already highly charged presidential election year.

Concerns were raised last night of political interference by the White House in the military's decision to go to trial in the middle of an election campaign in which the Republican frontrunner, John McCain, has made the fight against al-Qa'ida central to his election bid.

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"What we are looking at is a series of show trials by the Bush administration that are really devoid of any due process considerations," said Vincent Warren, the executive director head of Centre for Constitutional Rights, which represents many Guantanamo detainees. "Rather than playing politics the Bush administration should be seeking speedy and fair trials," he said. "These are trials that are going to be based on torture as confessions as well as secret evidence. There is no way that this can be said to be fair especially as the death penalty could be an outcome."

While few doubts have been raised, domestically or internationally, about the men's involvement in the attacks on New York and Washington, just about everything else about their treatment has been bitterly contested and is likely to continue to be contested, inside the courtroom and out. Everything is laden with potential controversy – the decision to try the six men together rather than individually, the proposed venue at Guantanamo Bay, where all six are being held, the threatened use of the death penalty, and perhaps the most controversial question of all: the admissibility of evidence gathered through waterboarding and other coercive techniques generally defined as torture.

Even Brig-Gen Thomas Hartmann, the Pentagon official co-ordinating the case, acknowledged yesterday that it could be several months before a trial begins and months more, if not years, before any death penalty – assuming it is enforced – is carried out.

General Hartmann was careful to say that he wanted the trial proceedings to be "as completely open as possible", with lawyers and journalists present in the courtroom – barring the possibility of some closed sessions to consider classified information. He stressed that the men would be regarded as innocent until proven guilty, just as they would in a civilian court. And he promised to provide "every piece of evidence, every stitch of evidence, every whiff of evidence" to the defendants' lawyers so they would be fully able to prepare for trial.

That did little to stop Clive Stafford Smith, the British lawyer who has worked on behalf of "enemy combatants" at Guantanamo, to issue a condemnation of the "kangaroo court". He said: "Anyone can see the hypocrisy of espousing human rights, then trampling on them. We will infuriate our allies who firmly oppose the death penalty. We will anger the world."

Aside from Mohammed, alleged to be the mastermind who planned and coordinated the September 11 attacks, the defendants are Mohammed al-Qahtani, labelled by US officials the "20th hijacker" who never made it on board any of the planes that were crashed; Ramzi Bin al-Shibh, an associate of Mohammed Atta's in Hamburg who is believed to have acted as an intermediary between the hijackers and the al-Qa'ida leadership; Ali Abd al-Aziz Ali, a nephew of Mohammed's suspected of acting as his chief lieutenant; Waleed bin Attash, believed to have trained the hijackers; and Mustafa Ahmad al-Hawsawi.

But contrary to General Hartmann's assurances, it is far from clear what rights any of these men will have. The Supreme Court, which struck down an earlier version of the military tribunal system, is expected to rule before July on whether the protections of the US Constitution apply to them.

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Several commentators noted yesterday that the Bush administration is taking a risk by trying to press ahead with the trials. Its previous efforts to pursue justice against suspected terrorists have been patchy, if not downright disastrous.

Zacarias Moussaoui, the French national previously labelled the 20th hijacker, escaped the death penalty at his civilian trial and emerged as a deeply disturbed individual scarcely capable of participating in a sophisticated guerrilla operation – much to the embarrassment of the federal prosecutors who tried him in civilian court in Virginia.

Jose Padilla, the US citizen accused of wanting to detonate a radioactive "dirty bomb", won the argument that he could not be held indefinitely in military custody without trial and went on trial in civilian court. He received a far lighter sentence than his prosecutors were seeking – 17 years instead of 30 to life.

The Bush administration appears to believe that, politically at least, it can win the argument by stirring up the country's emotions about the worst peacetime attack on its own soil.

Facing execution

* Khalid Sheikh Mohammed

The Pakistani, educated in the US, claims responsibility for 31 attacks and plots including the 9/11 attacks and the beheading of Wall Street Journal reporter Daniel Pearl. Accused of being military commander for al-Qa'ida's foreign operations. Captured in Pakistan in 2003 and taken to Guantanamo Bay from secret CIA prison. During interrogation, was subjected to simulated drowning technique known as waterboarding.

* Ali Adb Al-Aziz Ali

A nephew of Khalid Sheikh Mohammed and cousin of jailed 9/11 bomber Ramzi Yousef. Accused of facilitating the attacks by transferring $120,000 to US-based operatives and assisting nine hijackers on their way from Pakistan.

* Ramzi Bin al-shibh

The former room-mate of Mohamed Atta is accused of being a link between al-Qa'ida and the hijackers. The Pentagon says he helped find flight schools for the al-Qa'ida pilots.

* Walid Bin Attash

The Yemeni, who was raised in Saudi Arabia, is accused of running al-Qa'ida camp in Afghanistan where he trained two 9/11 hijackers. Has admitted planning the attack on the USS Cole, and has also claimed involvement in the bombing of the US embassy in Kenya.

* Mustafa Ahmad al-hawsawi

The Saudi national is accused of being a money-man for the 9/11 attackers. The Pentagon says he provided them with cash, Western clothing, credit cards traveller's cheques.

* Mohammed al-Qahtani

Officials say he was meant to be one of the hijackers but was barred from the US by immigration officials at Orlando Airport. Captured at Tora Bora caves in Afghanistan.