Hurricane season has officially begun in Puerto Rico, where some 11,000 people remain without power after Hurricane Maria storm hit the island nearly eight months ago.

Officials said it could take another two months to fully restore power to Puerto Rico’s 3.3m residents, extending what is already the longest blackout in US history. Still others warned that the repairs to the power grid completed after the Category 4 storm would not hold through another hurricane.

“The grid is there, but the grid isn’t there. It’s teetering,” said Hector Pesquera, Puerto Rico’s commissioner of public safety. Even if the next storm is a Category 1, he added, the power grid is "in such a state that I think we’re going to lose power”.

The latest report from the National Oceanic and Atmospheric Association (NOAA) said there was a 75 per cent likelihood of five to nine hurricanes occurring in the 2018 Atlantic hurricane season, which stretches from 1 June to the end of November. There is a 70 per cent chance that as many as four of those could be Category 3, 4, or 5 hurricanes, according to the association.

To prepare for this likelihood, the Federal Emergency Management Agency has left some 600 generators on the island – more than six times the number stationed there before Maria hit. The agency has also stockpiled 5.4m liters of water and more than 80,000 tarps in preparation for the next storm. Officials have told residents to stockpile enough emergency supplies to live as long as 10 days without help.

Donald Trump: Our response to Puerto Rico was ten out of ten

Meanwhile, government agencies are pouring billions of dollars into fixing the existing power structure and creating a new, more efficient one. Walter Higgins, the new CEO of Puerto Rico's Electric Power Authority, said the agency just awarded a $500m contract to MasTec to help with power restoration and the construction of a new grid. Cobra Energy received another $900m contract, and a third was being finalised.

The restoration effort has cost $3.8bn in federal funding so far. But one power authority worker said that 10 to 15 per cent of that work was not up to standard.

“The logistics were terrible. I give it an F,” said Fredyson Martinez, vice president of the power authority workers’ union. “Things need to be fixed.”

Bringing aid to Puerto Rico Show all 20 1 /20 Bringing aid to Puerto Rico Bringing aid to Puerto Rico Crew chief Kenney shelters under the blade of an HH-60 Blackhawk helicopter from 101st Airborne Division's "Dustoff" unit preparing to take off during recovery efforts following Hurricane Maria, in Isla Grande, Puerto Rico, October 6, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico An HH-60 Blackhawk helicopter from 101st Airborne Division's "Dustoff" unit takes off behind Crew Chief Alexander Blake and his fellow soldiers during recovery efforts following Hurricane Maria, in Morovis, October 5, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Crew member Bynum stands in tropical rain as a HH-60 Blackhawk helicopter from 101st Airborne Division's "Dustoff" unit prepares to take off during recovery efforts following Hurricane Maria, in Isla Grande, October 6, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico UH-60 Blackhawk helicopter pilot Chris Greenway receives a hug from a woman thanking him for water as he works with the First Armored Division's Combat Aviation Brigade during recovery efforts following Hurricane Maria, in Verde de Comerio, October 7, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico A man carries a case of water away from an HH-60 Blackhawk helicopter after soldiers working with 101st Airborne Division's "Dustoff" unit dropped off relief supplies during recovery efforts following Hurricane Maria, in Jayuya, October 5, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Crew chief Alexander Blake from 101st Airborne Division's "Dustoff" unit loads water into a helicopter during recovery efforts following Hurricane Maria, in Isla Grande, October 5, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Residents wait for soldiers in UH-60 Blackhawk helicopters from the First Armored Division's Combat Aviation Brigade to deliver food and water during recovery efforts following Hurricane Maria, in San Lorenzo Reuters Bringing aid to Puerto Rico An HH-60 Blackhawk helicopter from 101st Airborne Division's "Dustoff" unit lands in a field to avoid lightning during recovery efforts following Hurricane Maria, in Manati, October 5, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Residents hold their hands aloft to signal that they need water as UH-60 Blackhawk helicopters from the First Armored Division's Combat Aviation Brigade fly past during recovery efforts following Hurricane Maria, near Ciales, October 7, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Tropical rain splashes on a runway as HH-60 Blackhawk helicopters from 101st Airborne Division's "Dustoff" unit wait for weather to clear during recovery efforts following Hurricane Maria, in Isla Grande, October 6, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Pilot Eldwin Bocanegra Torres speaks with residents isolated by landslides in the mountains after unloading water and food from a helicopter during recovery efforts following Hurricane Maria, near Utuado, October 10, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Residents stand in front of wind-damaged trees as they wait for soldiers in UH-60 Blackhawk helicopters from the First Armored Division's Combat Aviation Brigade to deliver food and water during recovery efforts following Hurricane Maria, in San Lorenzo, October 7, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico The contents of a home are seen from the air during recovery efforts following Hurricane Maria near Utuado, October 10, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Thomas looks out of the window of an HH-60 Blackhawk helicopter from 101st Airborne Division's "Dustoff" unit, loaded with relief supplies, during recovery efforts following Hurricane Maria in Isla Grande, October 6, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico A message written on the rooftop is seen from the air during recovery efforts following Hurricane Maria near Humacao, October 10, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico A HH-60 Blackhawk helicopter from 101st Airborne Division's "Dustoff" unit lands in a field during recovery efforts following Hurricane Maria in San Sebastian, October 6, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Sergeant First Class Eladio Tirado, who is from Puerto Rico, looks for a landing spot for a UH-60 Blackhawk helicopter from the First Armored Division's Combat Aviation Brigade, during recovery efforts following Hurricane Maria near Ciales, October 7, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Boys carry water away from an HH-60 Blackhawk helicopter after soldiers working with the U.S. Army's 101st Airborne Division's "Dustoff" unit dropped off relief supplies during recovery efforts following Hurricane Maria, in Jayuya, October 5, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Sergeant First Class Eladio Tirado from the First Armored Division's Combat Aviation Brigade, who is from Puerto Rico, speaks with residents as he helps during recovery efforts following Hurricane Maria, in San Lorenzo, October 7, 2017 Reuters/Lucas Jackson Bringing aid to Puerto Rico Residents peek through a fence at helicopters from 101st Airborne Division's "Dustoff" unit that had parked in a locked field during recovery efforts following Hurricane Maria, in Lares, October 6, 2017 Reuters/Lucas Jackson

The news came on the heels of a study published in the New England Journal of Medicine, which found the death toll from Hurricane Maria could be as much as 70 times higher than official estimates. Harvard researchers said more than 4,600 people likely died in the storm – significantly more than the government’s estimate of 64.

President Donald Trump previously gave his administration's response to the hurricane a "10 out of 10," comparing it to a "real catastrophe" like Hurricane Katrina, which killed an estimated 1,833 people.

Responding to the new death toll on Wednesday, White House Press Secretary Sarah Huckabee Sanders said the president took the situation in Puerto Rico "extremely seriously".

"The two Category 4 hurricanes that hit Puerto Rico were historic, and we've responded with the largest FEMA operation in history," she said. "And we're going to continue to work with the people of Puerto Rico and do everything we can to be helpful."

Mr Trump has yet to comment on the study,