A top Socialist official on Thursday claimed Spain's former conservative government withheld early information of an Islamic link to the Madrid train bombings and blamed Basque separatists in a bid to win national elections three days later.

At issue in the testimony to a parliamentary commission is whether the government of then-Prime Minister Jose Maria Aznar (search) told Spaniards the March 11 terror attack was probably carried out by Islamic militants — not Basque separatists — as soon as evidence pointed that way.

The conservative Popular Party insists it was honest with the country. The Socialists, who went on to win the vote, say it wasn't.

"It was a disinformation operation seeking an electoral advantage," Alfredo Perez Rubalcaba, the Socialist spokesman in congress, told the commission Thursday about the attacks that killed 191 people and wounded more than 1,600.

"The government gave information, said many things to the media trying to convince (public opinion) that the attack was committed by ETA," Perez Rubalcaba said in reference to the Basque separatist group.

On Wednesday, three former Popular Party ministers steadfastly defended their government's early insistence that ETA (search) was were to blame for the bombings. When that turned out to be wrong, they told Spaniards that, too.

"The government told the truth with all the diligence it was capable of in those moments," former Foreign Minister Ana Palacio (search) said. "It acted with honesty and transparency."

"The government never lied at any moment," said former spokesman for the conservatives Eduardo Zaplana.

The timing of the recognition that Islamic militants carried out the attack is significant because if it had been ETA, that might have boosted the Popular Party in the March 14 elections, as the conservatives were perceived favorably as having cracked down successfully on that group. Most polls indicated they would win.

But if it were Islamic militants and the attack was seen as retribution for Aznar's support of last year's U.S.-led invasion of Iraq, that might boost the Socialists who opposed the invasion and immediately withdrew Spanish troops from the occupation after winning election. The Socialists upset the conservatives on election day.

Police officials indicated to the commission that their focus switched to Islamic militants before the government acknowledged that publicly. Police now say there is nothing to indicate any link with ETA.

Socialists argue that even after a van was discovered with detonators and an Arabic language tape, and the first arrests of Islamic suspects were made, former Interior Minister Angel Acebes (search) on March 13, the day before the election, still was largely blaming ETA.

"We thought ... and we made it known that there were solid reasons to doubt ETA was behind the attack and that there might be a participation of Islamic terrorists," Perez Rubalcaba said. "Nobody listened to us, or, they listened to us but that didn't change the government's attitude."

After meeting for a month, the commission was to decide whether to recess Thursday for the summer or continue hearings next week. The commission planned to hold final hearings in late August or early September, then make recommendations to Parliament for debate.