VIENNA: What if it was Al Qaeda? Security analysts said on Friday the jury was still out on the possible involvement of Muslim militants in the Madrid train bombings , for which a group aligned to Al Qaeda claimed responsibility in an email to an Arab newspaper.

Spain said Basque separatist group ETA was to blame for the bombs that killed nearly 200 people. But after the discovery of a stolen van with detonators and taped verses from the holy Quran, the government said no lines of inquiry could be ruled out.

If Al Qaeda or related militant Muslims were involved, the implications would be enormous: the first such strike in the heart of Europe, and the first in the West since the attacks on America on September 11, 2001.

It would show that the network, after confining itself for the past 2-1/2 years to attacks in mainly Muslim countries like the Gulf, North Africa, Turkey and South East Asia, was capable of hitting "the heart of crusader Europe" and girding for a fresh blow against America, if the email to al-Quds al-Arabi newspaper is to be taken at face value. And it would raise the threat level to European nations such as Britain, Italy and Poland which have closely aligned themselves with the United States in its war on terror and sent their troops to Iraq. Terrorism experts, however, are wary of jumping to conclusions.

"The jury is still out," said Sebestyen Gorka, a security analyst based in Hungary. He said if he was "60-40" inclined on Thursday to blame ETA, this had now slipped to 50-50.

He said the attacks were neither classic ETA nor classic Al Qaeda, and the claim of responsibility was a little too neat.

"Al Qaeda is well known for either not accepting responsibility or doing so very late," he said, adding that the email was "a little bit too fast, a little bit too clear".

David Claridge of Janusian Security Risk Management in London said: "There are clues in both directions. The Spaniards seem quite determined to insist it's ETA...(but) the style, everything about it seems to point to Muslim extremists."

If Al Qaeda were involved, he said: "It has massive implications...It's potentially Europe's 9/11 in terms of a wake-up call."

Al Qaeda involvement would raise big questions about European intelligence services and governments, who had not alerted their publics by raising threat levels.-Reuters