The suspected bomb which paralysed train traffic around Leiden station on Wednesday morning was a camera hung from a concrete pillar by an advertising agency, Nos reported late afternoon.

Passengers alerted railway officials at 07.30 this morning after spotting a plastic bag and camera taped to the pillar. The station was evacuated and train travel halted while the mysterious bag was checked by explosives experts.

Police issued a description of the white man seen hanging the camera from the pillar. Now it transpires the camera was placed there with official permission although the police and railway officials on duty on Wednesday morning were not aware of the fact.

The NS now wants to find out who the advertising agency had spoken to. The camera has been taken apart and rendered useless in the investigation, Nos said.