Democrats are demanding Donald Trump's administration "immediately" release billions of dollars in congressionally approved aid to Puerto Rico in the wake of devastating and ongoing earthquakes and aftershocks that have destroyed hundreds of homes and left two-thirds of the island without electricity.

Earthquakes began rocking the island in late December, kicking off thousands of tremors, including the biggest quake to hit the island in a century, and killing at least one person and causing more than $110m in damages.

The quakes have rocked the island so intensely that Nasa researchers say the damage is visible from space.

Puerto Rico is still waiting on billions in federal funding after 2017's catastrophic hurricanes, during which more than 3,000 people were killed in the storm and its aftermath and which left more than 1.5m people without power.

In a letter to the president sent on Monday, Vermont Senator Bernie Sanders and New York Congresswomen Alexandria Ocasio-Cortez and Nydia Velazquez demanded answers from Mr Trump, who they urged to direct his Federal Emergency Management Agency to "fully extend federal resources under the most expansive reading of the disaster declaration" that the president issued on 7 January.

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

Last week, House Speaker Nancy Pelosi said the administration's "ongoing withholding of funds appropriated by Congress to Puerto Rico is illegal".

Ms Pelosi's remarks followed reports that a power plant was damaged by the 6.4-magnitude earthquake that struck the island on 7 January, among a string of tremors that continue to shake the island.

Ms Velazquez, the first Puerto Rican woman to serve in Congress, joined Senate Minority Leader Chuck Schumer and several other Democrats in a letter to US Housing Secretary Ben Carson pleading for the "immediate and urgent" publication of materials for the release of $8.3b in grants earmarked for the island's recovery following Hurricane Maria's devastation.

In their letter to the president, Democrats said "it is unconscionable" that the "people of Puerto Rico have been dealing with hundreds of earthquakes and aftershocks — just two years after being ravaged by Hurricane Maria while tens of thousands of people are still living under tarp roofs".

The letter said residents are being forced to "resort to sleeping in roofless shelters due to the fear of being buried in their own homes" after another quake.

Roughly 70 percent of the island was built before earthquake-resistant building codes had been established.

"Let us be clear", the letter reads. "Postponing the disbursement of this vital assistance any longer — in the face of the humanitarian needs of Puerto Rico — is simply shameful."

The Trump administration has released only $1.5 billion of a nearly $10 billion aid package and has refused to release the remainder despite the island's years-long humanitarian crisis.

Last year, he called the island "one of the most corrupt places on earth" and said the congressionally approved aid was sent to "crooked pols".