The Spanish Interior Ministry says police have arrested 16 suspected Islamic extremists, including five linked to last year's train bombings in the capital, Madrid.
The ministry alleged the 11 other suspects had links to the group headed by the al Qaeda leader in Iraq, Abu Musab al-Zarqawi.
The arrests were made during raids by more than 500 police in a number of Spanish regions and in Spain's North African enclave of Ceuta.
More than 190 people were killed and 1,900 were injured when bombs exploded on four commuter trains in Madrid in March last year.