The estimated death toll from Hurricane Maria in Puerto Rico has risen to 2,975 - more than 45 times greater than the previous estimate.

Hurricane Maria hit the US territory last September, causing massive damage on the Carribean island.

Officials initially put the death toll at 64, but it was widely believed many more people died as a result of the devastating storm.

The new estimate of 2,975 is contained within a government-commissioned report from the Milken Institute School of Public Health at George Washington University.

Researchers found that people in lower income areas and the elderly faced the highest risk from the hurricane, although said all areas were hit hard by the storm and its aftermath.

They call on authorities in the US, Puerto Rico and around the world to develop methods to 'rapidly assess' the amount of people killed as a result of natural disasters.

The report also calls on officials in Puerto Rico to develop a new crisis and emergency risk communication plan.

Lynn R Goldman, a co-author of the report, observed: "The lessons learned from this report and subsequent studies will help not just Puerto Rico, but other regions in the U.S. and around the world that face the ongoing threat of hurricanes and other natural disasters.

"If enacted, the recommendations of this report could help save lives in Puerto Rico and beyond."

During a press conference, Puerto Rico governor Ricardo Rosselló said he accepted the findings, noting that he will set up a commission to implement the report's recommendations.

He said the new figure was an estimate but with a 'scientific basis'.

In a statement, the White House said the US government would continue supporting efforts to ensure 'accountability and transparency' following last year's deadline hurricanes.

It adds: "The American people, including those grieving the loss of a loved one, deserve no less."