The suspected terrorists who died in last weekend's blast had planned another major attack in Madrid (search), possibly during this week's Easter celebrations, a court official said Wednesday.
Police also fear Saturday's explosion that may have killed seven suspects and the subsequent arrests of other suspects could stir another cell of militants to mount a 'jihad,' or holy war, in Spain, said the official, who spoke on condition of anonymity.
A Spanish judge, meanwhile, jailed two more suspects on terrorism charges, a court official said.
Seventeen persons are now charged and in jail in the case.
The two questioned Wednesday by National Court Judge Juan del Olmo were Moroccans Rachid Adli and Abdelila el-Fouad. Both were jailed on terrorism charges.
El-Fouad was arrested last Friday at the border in Ceuta, a Spanish enclave on Morocco's northern coast. Adli was detained Tuesday in Madrid. Earlier, the court had erroneously reported that he had been arrested in Illescas, a town south of the capital.
Of the 17 in custody, six have been charged with mass murder, the rest with collaborating or belonging to a terrorist group. Thirteen of the total are Moroccan.
The March 11 attacks on four commuter trains left 191 people dead and more than 1,800 injured.
In the suicide blast Saturday, the court official said, explosives and other evidence found in the apartment indicated the suspects planned an imminent follow-up to the March 11 attacks.
Police also found a substantial amount of money, including a roll of notes worth $604 on the body of one of the militants.
Spain, a largely Roman Catholic country, marks Easter week with national celebrations that culminate on Sunday, Easter Day.
Fearing more attacks, the government ordered unprecedented security measures this week, when millions of Spaniards pack trains, planes and highways for holiday travel.
A bomb was found and dismantled Friday on a high-speed line between Madrid and Seville (search).
An Al Qaeda-linked group that claimed responsibility for the March 11 attacks sent a statement to the Spanish newspaper ABC saying the bomb was a warning of the havoc the group could unleash.
The group said it would turn Spain into "an inferno" unless Madrid withdrew Spanish troops from Iraq and Afghanistan. Spain has 1,300 soldiers in Iraq and 125 in Afghanistan.
On Tuesday, prosecutor Olga Sanchez asked Del Olmo, the investigating magistrate, to issue four more international arrest warrants. No information was available on those suspects.
Del Olmo last week issued a similar warrant for six suspects.
The government previously said three of those six were among at least five suspected terrorists who blew themselves up Saturday as special forces prepared to storm their apartment in the suburb of Leganes, south of Madrid. The court official said Wednesday that police now believe that recovered body parts belonged to seven people.
Police also are looking for three people who may have fled the apartment before the blast and are hiding out near Madrid, the newspaper El Pais reported. They may include one or more of the people sought in del Olmo's warrants, the paper stated.
Authorities believe ringleader Sarhane Ben Abdelmajid Fakhet, of Tunisia, and Moroccan Jamal Ahmidan — described as his right-hand man and the person who rented the house where the bombs used March 11 allegedly were assembled — were among those killed Saturday.
The investigation into the Madrid attacks has focused on the Al Qaeda-linked Moroccan Islamic Combatant Group (search). It is also connected to a group suspected in suicide bombings last year in Casablanca, Morocco, that killed 33 people.