MADRID, Spain (CNN) -- - Spanish police arrested 11 suspected Islamic radicals Tuesday in the Spanish enclave of Ceuta on Morocco's north coast, an Interior Ministry spokesman told CNN.

The operation struck at "international terrorism" and the 11 suspects are linked to a cell of the terrorist Salafist Group for Call and Combat, Spain's Interior Ministry said in a statement.

The detainees are suspected of being in the initial phase of plotting a terrorist attack, CNN partner station CNN+ reported, citing Interior Ministry sources.

The suspects were involved in recruiting and indoctrination for Islamic terrorist activities to carry out attacks and had connections to terrorists in Britain and Morocco, the Interior Ministry statement said.

Ceuta, a Spanish enclave that Morocco also claims, has a population of about 77,000, including Spanish Catholics. Ceuta's Muslim community comprises about 43 percent of the population, a local Muslim leader told CNN. Ceuta is near the Strait of Gibraltar.

Spanish police have sharply increased the number of officers fighting Islamic terrorism since the 2004 Madrid train bombings, blamed on Islamic terrorists. There have been numerous raids across the country in the past two years to detain suspected Islamic radicals.

Spain's largest-circulation newspaper, El Pais, reported last month that Ceuta has become a target for Islamic radicals, via Web site postings visited by al Qaeda adherents. The Web site note called for attacks on what it termed the "occupied city of Ceuta" and also against the other Spanish enclave, Melilla (pron: May-lee-ya) farther east on Morocco's north coast.

The 11 suspects arrested include two brothers of Hamed Abderrahaman Ahmed, the Interior Ministry statement said.

Abderrahaman Ahmed is a Ceuta-born Spaniard who had been held at the U.S. naval base in Guatanamo, Cuba, and then was returned to Spain, where he was convicted last year for membership in al Qaeda, but was later acquitted by Spain's Supreme Court.

The Interior Ministry's list of detainees also shows two other sets of brothers among those arrested on Tuesday. The suspects range in age from 23 to 38.

Police seized an air pistol, a large machete, a bullet-proof vest, forged documents and four computers and accessories, which were being analyzed, the Interior Ministry said.

The investigation against the suspects began in March 2005 at Spain's National Court in Madrid, which handles cases of terrorism.