(Adds background, detail, interior minister comment)
MADRID, Feb 14 Spanish police arrested three people suspected of trying to promote radical Islam on Thursday in the northern city of Vitoria, local police said.
The three distributed CDs and MP3 files calling for a "jihad" or holy war among the city's Muslim community, local police said.
The arrests come just over three weeks before a general election. Three days before Spain's last vote in 2004, Islamic militants killed 191 commuters in Madrid train bombings that are widely thought to have swung the election for Socialist party.
A month ago, Interior Minister Alfredo Perez Rubalcaba said Islamic militants may have been plotting attacks on Barcelona's metro system. Police have since released four of the 14 South Asians arrested and have acknowledged they found few explosives.
"Our unfortunate, very recent experience tells us that a cell's decision to move from shouts to violent acts can be very quick," Rubalcaba said in a radio interview on Thursday.
"That is the window police have to try and stop these kind of plots, so it is delicate and difficult."
Police began investigating the Vitoria cell in December and moved to arrest the three following an order from Spain's High Court.
Vitoria, the capital of the Basque region, is more used to security threats from guerrilla group ETA, which is fighting for an independent Basque state. (Reporting by Raquel Castillo; Editing by Matthew Tostevin)