POLICE were hailing them through loudspeakers, demanding that they come out with their hands up. The block of flats was surrounded and the seven men inside — Islamic militants wanted in connection with the Madrid railway bombings — had to choose between surrender or suicide.

So they anointed themselves with water from Mecca and dressed in white robes that they had made out of bedroom curtains. Then they stood in a circle around a bomb, chanting religious slogans until one of them detonated it. The explosion demolished much of the building in the Leganes suburb of Madrid.

Details of the last hours of some of those responsible for the March 11 terror attacks have left no doubt about their maniacal fervour. According to Spanish police, they made telephone calls around the world — three of them to London — to get the blessing of spiritual leaders before blowing themselves up instead of facing arrest on April 3.

They were well connected in the world of Islamic terror. It has emerged that they were linked to some of the world’s most wanted men, including Abu Musab al-Zarqawi, the Jordanian believed to have decapitated Nick Berg, an American civilian, in a horrific video released last week in Iraq.

At the same time the investigation has raised in Spanish minds an uncomfortable question that is certain to be the subject of national debate once all the leads have been exhausted: could police have prevented the attack that killed 191 people and led to the downfall of the conservative American-allied government?

Some of the bombers had previously been under police surveillance as suspected terrorists. One had been expelled from Spain in 1999 after being found in possession of a stolen car and was briefly detained by Spanish police only weeks before the bombings on four commuter trains.

Even more embarrassingly for the police, two men who helped the terrorists to get hold of the explosives were supposed to have been informants. The house on the edge of Madrid in which police believe the suspects assembled the bombs had been under surveillance a year ago after neighbours complained about moros (as Spaniards refer to Moroccans), coming and going noisily in the night.

They might berate themselves over missed opportunities but the police can also consider themselves lucky. They would have had nothing to go on had it not been for the failure of one of the bombs to go off. It was found strapped to a mobile telephone that led investigators to a phone card shop where Jamal Zougam, a Moroccan, was arrested.

That led to the arrests of several petty criminals and Moroccan extremists. They, in turn, put police on the track of Sarhane ben Abdelmajid Fakhet, a Tunisian economics student turned estate agent who was thought to be the operational co-ordinator of the attack. His suicide with six others in the flat has complicated efforts to understand and unravel the Islamic terrorist network in Spain. Even so, police believe they may have identified a figure higher in the chain of command than Fakhet.

Last week they were trying to discover the fate of Amer Azizi, a Moroccan whose name has been associated with almost every big Al-Qaeda attack since September 11, 2001.

Intriguingly, his fingerprints — along with those of 25 other people — were found in a house at Morata de Tajuna where the bombs hidden in sports bags on the Madrid trains are said to have been assembled. Police are awaiting a DNA sample from his family in Morocco to see if it matches that from an unidentified seventh set of remains found in the rubble of the Leganes flat.

Police believe that Azizi, a battle-hardened Al-Qaeda operative, was the brains behind the Madrid bombings, suggesting a more direct involvement of Osama Bin Laden’s network than had been suspected.

Azizi was the sponsor of at least two militants undergoing training in Afghan terrorist camps set up in the late 1990s by al-Zarqawi. He was also a member of Al-Tawhid, a Jordanian Islamist organisation that al-Zarqawi headed.

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