Spanish state radio reports another arrest in the probe of last week's deadly bombings in Madrid, bringing the total number of suspects held to 10.
Few details are available on the newest arrest in connection with the bomb attacks, which killed 201 people and wounded 1,500 others.
Earlier Thursday, officials announced they had arrested four new suspects, at least one of whom is a suspect in a terrorist attack in Casablanca.
Three of those detainees were arrested in the Madrid suburb of Alcala de Henares where authorities believe the bombs were planted on commuter trains. The fourth suspect was arrested in the northern part of the country.
Five other detainees, arrested just hours after the bombings last week, were scheduled to appear before Spain's highest criminal court Thursday, where a judge must decide whether to charge them or release them.
Spain also announced today it is declassifying intelligence documents related to the attacks, in order to prove it did not try to mislead the public in order to gain an advantage in Sunday's general elections.
The government says it initially had reason to blame the Basque separatist group ETA for the attacks. But authorities now suspect the al-Qaida terrorist network might have been responsible -- and that the motive may have been Spain's participation in the U.S.-led occupation of Iraq.
Public outrage over a perceived government cover-up is thought to have contributed to the victory of the opposition socialists, who opposed Spanish involvement in Iraq.