The train crash south of Paris which left six people dead was caused by a fault in the rail tracks, says the state rail company.
SNCF said a metal bar connecting two rails had become detached close to Bretigny-sur-Orge station.
Earlier, Transport Minister Frederic Cuvillier ruled out human error and praised the train driver for averting a worse accident.
Thirty people were injured in the accident, eight of them seriously.
The train had just left Paris on Friday afternoon and was heading for Limoges when it derailed at Bretigny-sur-Orge.
Giving its initial findings, SNCF management told reporters the connector had worked its way loose and become detached at points 200m from Bretigny station causing the train to derail.
The inquiry is now expected to focus on how the piece of metal had become detached, and checks on these components are to be carried out on the whole of the network.
Courtesy: BBC