MADRID, Spain — A radical Muslim cell broken up by Spanish police had been plotting to bomb the National Court, a hub of Spain’s investigations of Islamic terrorism, the interior minister said Tuesday.

Seven terror suspects were arrested Monday in Madrid and southern Spain, and anoter was arrested Tuesday in the northern city of Pamplona (search), Interior Minister Jose Antonio Alonso said. Most are Algerian, and some had contacts with militants elsewhere in Europe, the United States and Australia.

“This was an operation against radical Muslims. They were planning to commit terrorist attacks,” he told reporters at Parliament.

“They were talking about attacking the National Court, a judicial body. But the police do rule out any other kind of possibility,” Alonso said, adding that no explosives were found during the arrests.

Spanish newspaper El Mundo reported the plan involved detonating a truck containing 1,100 pounds of explosives outside the courthouse, located on a busy avenue in downtown Madrid.

Among the suspects identified were Smail Latrech, Ali Omar “Jelloul,” Djamel Merabet, Mourat Yala “Abu Anas,” Ahmed Mohamed and Magid Mchmacha.

Police said the operation was continuing and didn’t rule out more arrests and home searches.

The arrests were ordered as part of a probe by the court’s Judge Baltasar Garzon, Spain’s leading anti-terrorism magistrate. Since September 2003, Garzon has indicted 41 people on terrorism charges, including Usama bin Laden and other Al Qaeda suspects accused of the Sept. 11 attacks in the United States.

Another judge at the court, Juan del Olmo, is leading a probe into the March 11 train bombings in Madrid, which killed 191 people and have been blamed on Muslim militants linked to Al Qaeda.

Three days after that attack, conservatives in power who backed the Iraq war lost to Socialists in general elections amid widespread voter sentiment that then-Prime Minister Jose Maria Aznar had made Spain a target for Usama bin Laden’s terror group.

The footage of the March 11 train bombings, shown on Telecinco, started with dazed commuters milling about on a smoke-shrouded platform after one early morning explosion. Then, smoke flows toward the camera and people on the platform are apparently knocked over by another blast.

About five seconds later, a ball of orange flame erupts from a stopped train, filling the screen. The tape includes no sound, just images.

Minutes later, bodies are seen strewn on the platform amid pools of blood. Police and emergency medical staffers attend to them. A few minutes afterward, police and crews are seen screaming for people to evacuate the station and themselves running toward the escalator, fearing another explosion. Telecinco said this warning turned out to be a false alarm.

The footage appeared to have been taken from atop an escalator, looking down onto the platform.

Telecinco also aired two other pieces of March 11 video that had not been broadcast publicly.

One showed a gun-carrying, masked militant claiming responsibility for the attacks on behalf of Al Qaeda. The video was found near a mosque on the eve of the March 14 general election.

“We claim responsibility for the Madrid attacks, two and half years after the blessed conquests of New York and Washington,” the Arabic-speaking man said, according to Telecinco’s translation.

In the other video, made March 27 of this year, three hooded men wearing belts loaded with dynamite cartridges threaten more attacks against Spain unless it withdraw its troops from Afghanistan.

Those three are now believed to have been ringleaders of the March 11 bombing cell and among seven suspects who blew themselves up in an apartment outside Madrid on April 3 as police prepared to storm it.