MADRID, Dec 21 (Reuters) - Spain formally accused a Moroccan man of 191 counts of murder and membership of an armed group in an investigation into the Madrid train bombings, court sources said on Tuesday.

High Court Judge Juan del Olmo remanded 41-year-old Hassan el Haski in custody without bail.

A source close to the investigation has said Haski may be the leader in Europe of a militant Islamic group accused of carrying out the May 2003 Casablanca bombings, in which 12 suicide bombers and 33 others were killed.

Haski is one of four Moroccans, all suspected members of the shadowy Moroccan Islamic Combatant Group (MICG), arrested on Lanzarote, one of Spain’s Canary Islands, last Friday.

Del Olmo had issued a warrant for Haski’s arrest in connection with the March 11 bombings of Madrid commuter trains which killed 191 people.

The other three suspects were being questioned by Judge Baltasar Garzon, who is conducting a separate investigation of Islamist militants.

Prime Minister Jose Luis Rodriguez Zapatero announced on Tuesday that Spain would activate a special security plan to guard against the risk of a terrorist attack over the Christmas period.

Spanish police believe Haski fled a crackdown on suspected MICG members earlier this year in France and Belgium, and that he and the other Moroccans detained on Friday were building a logistical base for the group in the Canary Islands.

Former Interior Minister Angel Acebes said three weeks after the March 11 bombings that the probe was focusing on the MICG, a group officials say is closely linked to Osama bin Laden’s al Qaeda network.

‘Accusation’ in Spain means the court is saying there is a case to answer; formal presentation of charges comes later under the Spanish system."

The Madrid bombings were widely seen as retaliation for the former government’s decision to send troops to Iraq.