Palma de Mallorca (Spain), Oct 6 (IANS/EFE): A 21-year-old man arrested with 140 kg of explosives has admitted to Spain's national police that he planned to set off bombs at the University of the Balearic Islands, authorities said Friday.

Juan Manuel Morales Sierra also spoke of his "complete admiration" for the two teenagers who killed 13 people April 20, 1999, at Columbine High School in the US state of Colorado.

Morales is a "very intelligent, introverted, frustrated person" who has "problems with society and sympathy with Nazi symbols", police told the central government's delegate in the Balearic Islands, Teresa Palma.

The police also confirmed that Morales "acted completely alone", Palma's office said in a statement.

The probe that led to Morales' arrest was sparked by Internet postings in which he referred to the perpetrators of the Columbine massacre as his "idols".

Eric Harris and Dylan Klebold gunned down 12 of their classmates and a teacher before turning their guns on themselves.

Spanish police were alerted to Morales' web postings by a Venezuelan journalist living in Japan, who came across the comments while doing online research about mass killings of students.