Pierre Izard, another SNCF official, said the metal piece "moved into the center of the switch and in this position it prevented the normal passage of the train's wheels and it may have caused the derailment."
Although for now it appears track failure was the cause of the crash, Pepy added: "There can be no (definitive) answer in a few minutes, in a few days." He also said that all of the approximately 5,000 metal pieces on switching systems around France will be checked.
The train was about 12 miles (20 kilometers) into its 250-mile (400-kilometer) journey to Limoges.
Passengers and officials in train stations throughout France held a minute of silence at noon to commemorate the accident. Hundreds of thousands of people were expected to take trains this weekend to the coast and mountains and to see family. Summer weekends are always busy on France's extensive rail network, but this one is typically one of the busiest because of Bastille Day.
Fuzeau gave the latest casualty figures, saying that in addition to the dead, 22 people remained hospitalized, two of them in a life-threatening state. Nearly 200 people had initially been treated for injuries, either at the scene or at hospitals.
The crash was the country's deadliest in years, but Transport Minister Frederic Cuvillier said it could have been worse and praised the driver who sent out an alert quickly, preventing a pileup. However, Cuvillier acknowledged that there was some criticism that France hasn't invested enough in maintaining infrastructure.
Willy Colin of the Rail Users Association was among those who claimed the Paris-Limoges inter-city line was neglected in favor of more high-profile fast-train lines. He said on BFM-TV that trains on the line were among the oldest, calling them "garbage trains."
The transport minister said no link can immediately be made between the state of the line and the accident.
"For the moment we have no information that allows us to confirm that the dilapidation of the network was the cause of this derailment," he said on French television.
Ganley reported from Paris. Associated Press writer Sarah DiLorenzo also contributed to this report from the French capital.