Austrian security services arrested a 25-year-old Moroccan asylum seeker suspected of plotting a terror attack in the city of Salzburg, prosecutors said on Tuesday.

Authorities said they had been informed in recent months an unidentified man "discussed an alleged terrorist attack in Salzburg in the period around Christmas/New Year," the prosecutors' office said.

Police have accused the man of belonging to a "terrorist organisation", and said that though a search of his accommodation in a building housing refugees in Fuschl am See on Monday (19 December) found no trace of weapons or other suspicious materials they could not rule out that he was planning an attack.

"Along with smaller amounts of drugs and cash in the amount of more than €8,000 ($8,300) several electronic devices were seized, which will be assessed," the prosecutors' office said.

Six other people were held in the raid on suspicion of drugs offences.

It comes after Austrian authorities announced that security would stepped up at Christmas markets after 12 people were killed when a truck was driven into crowds at an event in Berlin.

Salzburg is one of Austria's most popular tourist destinations, and is famed for its Christmas market.