Journalists and citizens were evacuated and the cause of the risk was not disclosed, Anadolu Agency reported.

Police later reopened the area to pedestrian traffic and access to and from the media centre returned to normal.

France increased security measures to prevent a new sabotage on train lines.

French transport minister Patrice Vergriete told the LCI channel that after the arson attacks Friday, security and surveillance of the railway network have been significantly strengthened.

Vergriete noted that more than 1,000 employees and 250 security personnel have been deployed to monitor the railway network, and gendarmerie helicopters and 50 drones have been mobilised.

He indicated that officials anticipate disruptions to train services Sunday and operations are expected to return to normal starting Saturday.

He said an investigation into the attacks is ongoing and perpetrators have not yet been identified.

Vergriete said authorities did not receive warnings from intelligence services regarding the arson attacks and €5 million (US$5.4 million) has been spent to enhance the security of the railway network in the Île-de-France region, which includes Paris, as part of the Games.

Hours before the opening ceremony of the Games on Friday, it reported train lines were set on fire in Pagny-sur-Moselle, Courtalain and Croisilles across France. An arson attempt on a train line in Vergigny was prevented.