A prosecution official says Czech authorities have detained three suspects for allegedly planning a terrorist attack on a train.

Stepanka Zenklova, a spokeswoman for Prague's state prosecution, on Wednesday said the three, who have not been identified, face up to life in prison if tried and convicted of terrorism.

Zenklova says three other people have also been investigated as suspects in the case, one for illegal weapons and two others for knowing about the attack plan and failing to intervene.

She said an unspecified dangerous weapon was seized by police during raids last week when police detained the six suspects. Three of them remain in police custody.