From its first day on the job this week, a Spanish parliamentary panel investigating the March 11 train bombings in Madrid and the government's response to the carnage has run up against political maneuvering, accusations of partisanship and suspicion that key facts will remain obscured.

As in the special U.S. commission's investigation of the Sept. 11, 2001, attacks in the United States, survivors of the bombings and family members of those killed are taking a forceful and prominent role in the Spanish probe. Many are raising uncomfortable questions for both the Popular Party (PP), which was in power at the time of the bombings, and the Socialist Workers' Party, which unseated the Popular Party in an election three days after the attack.

Among other things, victim groups want the panel to determine whether Jose Maria Aznar, the prime minister at the time of the bombings, or current Prime Minister Jose Luis Rodriguez Zapatero, then the opposition leader, received advance warnings of the plot.

Aznar's party faces accusations that it ignored threats by Islamic terrorists before March 11 and that it then deliberately tried to mislead people that the Basque separatist group ETA carried out the attacks. The alleged motive was to keep voters from punishing Aznar's party for its unpopular support of the war in Iraq.

The Socialists have been accused by a newspaper often sympathetic to the Popular Party of possibly knowing, through contacts in the national police, more before and after the attacks than they have let on and playing on public fears to win the election.

"The PP is not interested in the first part, the possible errors of prevention in the work of the intelligence services," said Edurne Uriarte, a political scientist and terrorism expert. "At the same time, the Socialist party is not very interested in analyzing the second question, which is what happened between the 11th and 13th of March." As a result, she said, "There is not a great deal of confidence in Spain, among citizens, analysts, journalists, about the possible results of this committee."

Before the attacks, which officially killed 190 people and an unborn fetus, and injured more than wounding close to 1,800, al Qaeda had issued general threats of attacks on Spanish targets as retaliation for Aznar's dispatch of troops to Iraq. But the newspaper El Mundo has alleged that specifics had come to light before March 11.

The newspaper contends that two police informants told their handlers that Middle Easterners in Spain were buying explosives and passed along details about the men and where they lived. This information, the newspaper contends, might have reached Socialists who held senior security positions. Immediately after the bombing, according to El Mundo, these people possibly briefed their party's leaders on the probe even before government ministers received the information.

In the investigation of the government's response, blame must be assigned "legally, not just politically," said Clara Escribano, who suffered spinal damage, a perforated eardrum and shrapnel wounds when a bomb exploded aboard her train near the El Pozo station. She now heads a group called 11-M Victims Association. The goal should be "that those people who committed mistakes with information, who kept us tricked for a certain period of time be brought to light and pay for their guilt," she said.

Added Maria Culebras, who lost a childhood friend and other friends in the attacks: "We here think the same thing happened like in the United States with the twin towers. There were warnings, and it could have been avoided."

The 15-member panel, whose legal powers remain unclear, includes people from all political parties in the parliament. It held its first meeting Wednesday, behind closed doors, to consider what papers it could examine. It has asked for all government documents on the bombings, but officials have said classified documents will be shared on a case-by-case basis.

Jockeying has been evident in debate over who will testify. Political parties are allowed to in effect nominate witnesses, but it remains unclear whether other parties will have power to veto witnesses. So far, Zapatero has not been called by anyone, and neither the Socialists nor the Popular Party has proposed Aznar, who now holds a faculty position at Georgetown University. However, Aznar's name was put forward by three smaller regional parties, some of whose members accused the two large parties of having a secret "non-aggression pact" to prevent their two leaders from testifying. Mariano Rajoy, the new Popular Party leader in parliament, said Thursday that Aznar is willing to testify. The Socialists have said that Zapatero need not testify because he held no office in the government at the time of the attacks.

Victims are following the proceedings closely. In interviews earlier this month, some said that they did not immediately blame Muslim attackers but do now.

"When the first bomb went off, I thought it was ETA," said Angel Rodriguez Peon, a 51-year-old postal worker who was seated on the upper level in the fifth car of a train when a blast went off in the fourth car. A second blast hit car number five, directly beneath Peon, wounding him in the legs and chest.

He said when he learned later that there were four explosions on his train, he changed his mind about the culprits. "It's not the way ETA has operated," Peon said. "They usually don't go against the working people." Its usual targets have been police officers, officials and journalists.

By openly blaming the Popular Party, the 11-M group is in sharp opposition to another, longstanding set of victims in Spain, relatives of the approximately 800 people killed by ETA operatives. Many ETA victims were from the Spanish security services, where support for the Popular Party and its no-compromise policy toward ETA has been strong.

One point of conflict had involved compensation. Before paying it out, the government wanted the Madrid group to become part of the existing Victims of Terrorism Foundation, which the families of ETA victims dominate. Escribano wants to keep the 11-M victims separate. A meeting this week between the two groups appeared to have resolved the compensation issue.

Clara Escribano, left, and Mari Culebras, work in a Madrid office helping victims of the March 11 train bombings fill out the forms needed to get compensation. Escribano was hurt in the blast.