Madrid, Spain ? Armed with what they said was new evidence, Spanish officials remained adamant Friday that they think the Basque separatist group ETA, not the al-Qaida terrorist network, was behind the morning rush-hour train bombings that rocked this capital city Thursday.

With the death toll nearing 200 and dozens of the wounded still in critical condition, Interior Minister Angel Acebes announced Friday evening he was more convinced than ever that ETA was to blame for the 10 explosions that ripped through three Madrid commuter rail stations just as people were disembarking on their way to work.

Acebes said the bombs consisted of satchels filled with 20 to 30 pounds of dynamite, set off by a cell phone.

He said the dynamite chemically matched 1,100 pounds of explosives seized in February from an ETA van heading toward Madrid, and that the satchel and cell phone setup matched that found on two ETA members when they were arrested on Christmas Eve at a northern Madrid commuter rail station.

“This explosion had a very similar modus operandi used by the terrorist group ETA,” he said.

Millions of Spaniards filled the streets of Madrid and other major cities Friday in tribute to the dead and injured and to protest the attacks. Spanish Prime Minister Jose Maria Aznar marched in front of one group in Madrid, and columns of demonstrators stretched for miles.

Spanish flags with black banners hung from light poles and balconies throughout the capital.

“Snakes,” “assassins” and “murderers” were among the insults hurled in unison by hundreds of demonstrators at a time. Placards proclaimed that “A people united will never be defeated” and “ETA No.”

If the crowd seemed united in its denunciation of ETA, there was still much discussion from Washington to Madrid about responsibility for the attacks.

In Washington, the FBI said it hadn’t dispatched any agents to Spain and wouldn’t do so unless the Spanish government requested them. No Americans died in the blasts, though the dead included citizens of at least 11 countries.

Aznar offered citizenship to all illegal residents of Spain whose relatives were killed in the blasts. He said the government thought they would be essential to identify the final 70 bodies at the city’s makeshift morgue. The dead are thought to be illegal immigrants whose relatives are afraid of being deported if they come to claim the bodies.

U.S. Senate Majority Leader Bill Frist, R-Tenn., said he’d been briefed on the attacks and that American officials were interested in any similarities to the Sept. 11, 2001, attacks in the United States.

“The patterns — multiple sites, multiple stations,” Frist said. “Very much like having multiple places here in this country.”

U.S. officials said the evidence cut both ways. Asa Hutchinson, the Homeland Security Department’s undersecretary of borders and transportation, said American intelligence agencies had detected no spike in “chatter” among al-Qaida-related groups before the attacks.

Many Spaniards, particularly those who support the Socialist Party in Sunday’s elections, suggested that Aznar’s government might not be willing to disclose an al-Qaida link until after the vote, for fear of hurting the chances of Aznar’s Populist Party holding on to power.