Puerto Rico was hit by a major blackout on New Year's Eve, and the cause remains under investigation
Puerto Rico was hit by a major blackout on New Year's Eve, and the cause remains under investigation AFP

A major power outage plunged much of Puerto Rico into darkness on New Year's Eve, with the US island territory's electric utility saying restoration could take up to two days.

The "island-wide blackout" began at 5:30 am Tuesday (0930 GMT), Luma Energy, which manages power transmission on the island, said in a social media statement.

It said preliminary findings pointed to a fault in an underground cable as the cause, although the outage remained under investigation.

Jose Perez, director of external affairs at Luma, told AFP that the fault "caused a cascade effect" leading to the general blackout.

"We have already begun the restoration process for some customers, and the entire process will take 24 to 48 hours," Luma said.

US President Joe Biden was briefed on the outage, the White House said, noting that federal assistance was available if needed to speed up the restoration.

"This is a long and arduous process that requires local and federal collaboration," Puerto Rico Governor Pedro Pierluisi said on X, adding that he had asked the Federal Emergency Management Agency to "continue facilitating the projects we have begun."

The blackout came as the Caribbean island entered its high season for tourists visiting from the wintry US mainland, and just hours ahead of New Year's Eve celebrations.

Luma said in a later statement that service had been restored to some critical facilities, including a medical center and hospital in the capital San Juan.

The agency had restored service to more than a million customers, approximately 69 percent of those affected, by 3:00 am local time (0700 GMT) Wednesday, according to its emergency response dashboard.

"The truth is that we have been dealing with this problem for a while," said Ismael Perez, a resident of Dorado who expressed frustration with the island's power grid.

He said he was concerned that residents could be left without power for more than two days.

Buildings stood in the dark early Tuesday while traffic intersections were without stop lights, with only the headlights of vehicles lighting up the streets.

Pierluisi said in a social media post that officials were in communication with Luma and others about the blackout.

"We are demanding answers," he said, adding that the public should be informed of the measures being taken to restore service.

Luma said it would provide regular updates on social media.

Puerto Rico, a Spanish-speaking archipelago, came under US control in 1898 and has faced perennial infrastructure issues, exacerbated by the devastating Hurricane Maria in 2017.

The Puerto Rican power grid has suffered frequent outages since then.