At least 76 were injured in the serious rail incident on a train from Novosibirsk to Adler.
The accident happened on a train which had travelled some 4,000 km from Novosibirsk, when the train was only 140km from its destination
At least 12 people were hospitalised after five carriages overturned on a train reportedly carrying school graduates among many holidaymakers to Adler, the district of Sochi which will host the opening of the 2014 Winter Olympics and many key events.
'Seventy have minor injuries, six persons received injuries of moderate gravity,' said an Emergencies Ministry spokesman. 'No one was killed or seriously injured'.
Altogether 618 people were on the train from Siberia's largest city. The accident took place in the railway section between stations Krylovskaya and Kislyakovka at 16:52 Moscow time on Sunday in Krasnodar region.
The accident happened on a train which had travelled some 4,000 km from Novosibirsk, when the train was only 140km from its destination.
It was not immediately clear what caused the derailment. At the time, temperatures were 33C which could have led to the tracks buckling, said one source.
'One of the key causes of the accident is fact that the rails do not conform with the standards because of the hot weather, among other reasons,' said a source in the local emergencies department, though it seemed too early to have a definitive cause.
There were also claims that vandalism might have led to the incident, but there was no clear evidence.
Emergencies Minister Vladimir Puchkov said: 'More than 70 people were hurt, 12 of them were hospitalised. This number will increase. An An-148 plane might be sent to evacuate people hurt in the train accident to Moscow and St Petersburg', he added.
Puchkov promised that 'each of those hurt should be given concrete specialised help' while psychologists were working with many of the passengers traumatised by their experience. The North Caucasian railway arranged to buses to evacuate the train's passenger to Krylovskaya. The local administration was providing accommodation.
Archeologists discovered a new stone bracelet, two sharp pins, a marble ring and fox tooth pendants.