Spanish police arrested three suspected members of Al-Qaeda who had enough explosives to blow up a bus and were thought to be planning an attack in Spain or elsewhere in Europe, the government said Thursday.
"One of the suspects is a very important operative in Al-Qaeda's international structure," Interior Minister Jorge Fernandez Diaz said, adding that it was one of the biggest ever police investigations against the Islamist group.
"There is a clear indication that those arrested could have been planning an attack in Spain or in Europe," he told a news conference.
Police found the explosives in a flat in the southern town of La Linea de Concepcion in Andalucia, where one of the suspects was detained on Wednesday, the minister added.
The two other suspects were arrested earlier Wednesday in the central province of Ciudad Real while travelling by bus from Cadiz to Irun near the French border, he said.
The suspects are a Turkish national and two others from former Soviet republics which the minister did not name.
Earlier on Thursday Cadena Ser radio, citing police sources, said the suspects were two Chechens and a Turk and had poison in addition to explosives.
The minister said police had so far found no poison but he said the secret services of other nations had informed Spain that one of the suspects "has extensive experience in the manufacture of poison and car bombs."
Several Islamic extremists have been arrested in recent years in Spain, especially in Catalonia in the northeast.
In March police arrested a suspected member of Al-Qaeda in the eastern city of Valencia on terrorism charges. They said he ran one of the world's most important jihadist forums dedicated to recruitment and indoctrination.
The man, who has Saudi citizenship, was known within the organisation as "Al-Qaeda's librarian", Diaz told reporters at the time.
On March 11, 2004, bombs exploded on packed commuter trains in Madrid, killing 191 people and wounding 1,841 others in a strike by a local cell of Islamic extremists carried out in the name of Al-Qaeda.
Twenty-one people, mostly Moroccans, were convicted of involvement in those attacks.