Wednesday, May 5, 2004 Posted: 2247 GMT (0647 HKT)
The brazen morning rush-hour terror strikes at city train stations also wounded at least 1,400.
The initial belief among officials was that ETA, designated a terror group by the United States and the European Union, was responsible.
But Spanish Interior Minister Angel Acebes said authorities were investigating a van found in the town of Alcala de Henares, outside Madrid, with at least seven detonators and an Arabic tape with Koranic teachings.
The tape contained no threats and is a type available commercially. The van was stolen last month.
The new line of investigation, sparked by a citizen's tip, raised the possibility of a link to Islamic militants.
A U.S. official cautioned it was "still too early to say" whether the bombings were the work of ETA or other terror groups, including al Qaeda.
Referring to a statement that claimed responsibility and was attributed to a group allegedly affiliated with al Qaeda that was received by a London-based Arabic-language newspaper, the U.S. official said "keep in mind we often see false claims of responsibility," and that even for attacks it did commit, "al Qaeda frequently takes no public credit."
Khalid al-Shami, political editor of Al Quds Al Arabi newspaper in London, told CNN the letter was from Abu Hafs al-Masri, which he said was affiliated with al Qaeda.
He said the group has issued credible claims in the past and claimed responsibility for Monday's attacks in Istanbul on a Masonic lodge.
But intelligence sources have consistently told CNN that Abu Hafs al-Masri does not speak for al Qaeda, and there is a question about whether it exists at all beyond one person with a computer and a fax machine. (Full story (http://edition.cnn.com/2004/WORLD/europe/03/12/spain.blasts.alqaeda/index.html))
In an interview on Radio Popular in Basque Country, Arnaldo Otegi, leader of banned radical political party Batasuna, said he did not believe ETA was responsible.
The attacks could have been "an operation by sectors of the Arab resistance," he said. Before the discovery of the van, Acebes said Otegi was simply trying to confuse the situation.
The scale of the attack was unlike anything ETA has ever carried out. The highest death toll in any ETA-linked attack was in 1987 -- when 21 were killed in a Barcelona supermarket blast.
Attacks blamed on or claimed by ETA through the years have killed 800 people in Spain. The group has been fighting for an independent homeland in northern Spain.
Authorities also said ETA usually posts warnings and claims responsibility for the actions.
One Basque official called it the worst terror attack in Spanish history.
The Spanish ambassador to the United States, Javier Ruperez, who said he believes ETA was responsible, said "in a way it is" Spain's September 11, referring to the 2001 terror attacks in New York and Washington.
Spain's Prime Minister Jose Maria Aznar addressed the nation and condemned the terrorists attack, saying ETA must be crushed, and opposed negotiations with them.
"There is no possible negotiation with these killers," he said.
Countries across the world expressed their outrage. (Global reaction) (http://edition.cnn.com/)
U.S. President Bush sent his condolences to Spain, one of the top U.S. allies in the Iraqi war, saying "we weep with the families" and "we stand strong with the people of Spain."
British Foreign Secretary Jack Straw called it "a disgusting assault on the very principle of European democracy."
The U.N. Security Council unanimously passed a resolution condemning the attack "in the strongest terms."
The attacks took place at the height of Thursday's rush hour when three separate trains were hit by near-simultaneous explosions before 8 a.m. (0700 GMT) along the southern part of Madrid's train network, officials said.
Acebes said there were multiple explosions at the Santa Eugenia, El Pozo and Atocha stations, and three other bombs were found and detonated by police.
The deadliest blast happened on a train entering Madrid's main Atocha station, according to Acebes.
Acebes said suspicion focused on ETA because the modus operandi was similar in December and February incidents, and the type of explosives matched those typically used by ETA. Anti-terror officials said the dynamite was stolen in France three years ago.
Survivors described scenes of chaos and panic.
"The worst was people screaming for help inside the train and there was nothing we could do," one survivor told CNN's Spanish sister network, CNN+.
People in tears walked away from the city's main Atocha station in droves as rescue workers carried bodies away from the scene. (Eyewitnesses (http://edition.cnn.com/2004/WORLD/europe/03/11/spain.blasts.scene/index.html))
The attack took place ahead of Sunday's general election in which Spain's conservative ruling Popular Party -- which has taken a hard-line stance against ETA -- is leading in the polls.
After the blasts, all political parties announced they were suspending campaign rallies, but there has been no word that elections would be suspended.
The government called for a three-day period of mourning, and impromptu anti-ETA demonstrations broke out in Madrid and other cities.
Spanish police -- who have foiled several recent bombing attempts by ETA -- were on high alert for terror attacks ahead of Sunday's vote.
Spain's King Juan Carlos, who spent the day visiting the wounded, expressed his sorrow to the families of the victims on TV in a brief taped address.
"Your king is suffering with you," he said.
He called the perpetrators "cowards and murderers" who "should suffer for the crimes they have committed."
Spain must be resolute in fighting the violence, he said. "There is no other option but unity, firmness and serenity in the fight against terrorism."
Shortly after the blasts, Basque leader Juan Jose Ibarretxe held a news conference from the Basque capital of Vitoria to condemn the violence and to call for demonstrations against ETA.
Basque member of parliament Gustavo Aristegui -- who was in Madrid at the time of the attack -- also blamed ETA.
"This is probably Spain's worst terrorist attack in history -- not probably, surely our worst terrorist attack ever," Aristegui told CNN. "There are people that are real monsters that are trying to blackmail the whole society through acts of terror."
Spanish Foreign Minister Ana Palacio placed the blame squarely on ETA: "We knew they are preparing a very big terror attack."
"ETA has a very clear pattern in its activities and we unfortunately have a long experience in dealing with them," she said.
On February 29, Spanish police seized more than 1,000 pounds of explosives and arrested two suspected ETA members who were planning to carry out an attack in Madrid, an official said.