PUERTO Rico has conceded that Hurricane Maria killed more than 1400 people on the island last year and not just the 64 in the official death toll.

The government acknowledged the higher death toll with no fanfare in a report submitted to Congress this week in which it detailed a $US139 billion ($187 billion) reconstruction plan for the island.

That quiet acknowledgment was first reported by The New York Times.

Puerto Rican officials have admitted that more than 64 people likely died from the powerful storm that knocked out the power grid and caused widespread flooding that made many roads impassable.

But a more exact number has been a matter of debate that the government has sought to end by commissioning an academic study due out in coming weeks.

The Puerto Rican report to US Congress put the number of US citizens who died due to Hurricane Maria at 1427 but the US government has refused to say all those deaths are associated with the hurricane.