Hurricane Maria could strengthen within the next day or so, the United States National Hurricane Centre has said, as the storm continues to lash the northeastern Dominican Republic.

The category 3 hurricane thrashed parts of the Dominican Republic with heavy rain and high winds after making a direct hit on Puerto Rico, causing severe flooding and cutting power to the entire island.

Maria has killed at least 10 people as it raged through the Caribbean. It ripped roofs off almost all structures on the island country of Dominica, where seven people were confirmed dead. The toll is expected to climb when searches resume.

The eye of the hurricane had previously shrunk to a compact 10 miles across, prompting warnings it was developing "the dreaded pinhole eye."

Such an effect means an extremely strong hurricane could get even mightier, Brian McNoldy, a hurricane researcher at the University of Miami, told the Associated Press.

He compared it to when a spinning ice skater brings in their arms and rotates faster. "You just don't see those in weaker hurricanes," he added.

The faster the storm spins, the more powerful it is likely to be.

Yesterday evening, meteorologists observed the reappearance of Maria's pinhole eye.

Although the hurricane weakened as it went over land in Puerto Rico, it picked up strength early on Thursday as it passed over warm Caribbean waters.

Puerto Rico without power after being hit by Hurricane Maria

Previously a category 5 with 175mph winds, Maria hit Puerto Rico as the third-strongest storm to mke landfall in the US, based on its central pressure. It was even stronger than Hurricane Irma when that storm roared into the Florida Keys earlier this month.

Hurricane Irma sideswiped Puerto Rico on 6 September, leaving more than one million people without power but causing no deaths or widespread damage like it did on nearby islands.

Maria, however, blew out windows at some hospitals and police stations, turned some streets into roaring rivers and destroyed hundreds of homes across Puerto Rico, including 80 percent of houses in a small fishing community near the San Juan Bay, which unleashed a storm surge of more than four feet.

The hurricane was still dumping rain overnight in Puerto Rico, where crumbled red roof tiles lay scattered across many roads, and residents sidestepped and ducked under dozens of black power lines still swaying in heavy winds.

Maria was expected to pick up strength as it churns toward the Turks and Caicos Islands and the southeastern Bahamas.

The storm would then move north in the Atlantic Ocean over the weekend and there was no indication whether it would hit the continental United States.