Forensic investigators in India have raised questions over an attack which killed almost 60 Hindus and led to widespread anti-Muslim riots in the western state of Gujarat.
Hindu pilgrims travelling by train were said to have been attacked by a Muslim mob in the town of Godhra which forced the train to stop and set fire to one of the carriages.
But a report by forensic scientists in Gujarat says it does not appear that the fire on the train was started from outside.
The incident, which took place last February, sparked some of the worst Hindu-Muslim riots in decades in which it is estimated about 2,000 people, most of them Muslims, died.
Fifty-nine people, mostly women and children, died in the attack, which sparked weeks of anti-Muslim violence across Gujarat.
New evidence
Now, conclusions reached by official forensic investigators contradict earlier accounts of the incident.
They say the evidence suggests the fire was started inside a carriage, not by a mob outside.
Their findings will form part of police evidence and have not yet been made public.
Riots
The new theory does not answer the key question of who started the fire and why and seems at odds with eyewitness accounts given at the time.
Some independent reports into the anti-Muslim riots which followed the train fire have accused the state government of collusion in the violence.
An internal British report said the riots, far from being spontaneous, were pre-planned and carried out with the support of the chief minister.
India's central government has dismissed such allegations and refused to criticise or replace the chief minister, Narendra Modi, who is part of the same political party, the BJP.
Rally called off
On Tuesday, Mr Modi's government postponed a Hindu rally planned for Thursday amid fears it could reignite violence between Hindus and Muslims.
Billed as a celebration of Gujarat's achievements, the Gaurav Yatra chariot processions were being organised by the chief minister's Bharatiya Janata Party (BJP).
India's National Human Rights Commission had voiced fears that the rally might revive religious violence in the state.
While Mr Modi postponed Thursday's event, he has not changed the timing of another Hindu mass celebration in Gujarat scheduled for 12 July.
Correspondents say that the authorities will wait to see how the 12 July event passes off before deciding on a new date for the Gaurav Yatra.