Madrid, Oct 5 (IANS/EFE): Spanish police said Thursday that a 21-year-old engineering student arrested with explosives planned a Columbine-style attack at the University of the Balearic Islands.

The suspect, identified only by his initials, J.M.M.S., was detained Wednesday in Palma de Mallorca after a five-month-long investigation.

The probe was sparked by Internet postings alluding to the events of April 20, 1999, at Columbine High School in the US state of Colorado, where a pair of teenagers gunned down 12 of their classmates and a teacher before turning their guns on themselves.

Besides 140 kg of explosives ordered over the Internet, police found a diary in which J.M.M.S. expressed hatred of society and his fellow students and outlined a scheme to plant shrapnel-filled pipe-bombs around the university campus.

The suspect's apprehension likely averted a massacre, Spanish Interior Minister Jorge Fernandez Diaz said, hailing police for carrying out an "exceptionally brilliant" operation.

"It is once again made plain that the police protect the lives, safety and freedom of Spanish citizens," the minister said.