A senior police officer's sworn statement to India's Supreme Court alleges that Gujarat Chief Minister Narendra Modi deliberately allowed anti-Muslim riots in the state.
More than 1,000 people were killed in the violence in 2002.
Sanjiv Bhatt says he attended a meeting at which Mr Modi is alleged to have said that the Hindus should be allowed to vent their anger.
Mr Modi has always denied any wrongdoing.
'Vent their anger'
The riots began after 60 Hindu pilgrims died when a train carrying them was set on fire.
Sanjiv Bhatt was a senior police officer in the Gujarat intelligence bureau during the 2002 riots.
In a sworn statement to the Supreme Court, he said that his position allowed him to come across large amounts of information and intelligence both before and during the violence, including the actions of senior administrative officials.
He also alleges that, in a meeting in the night before the riots, Mr Modi told officials that the Muslim community needed to be taught a lesson following an attack on a train carrying Hindu pilgrims.
The Gujarat government has responded to the allegations by saying they have already testified before a special panel investigating the riots and will wait for the court's verdict.