(Adds latest data, comment from Anguilla resident)
Sept 17 (Reuters) - A second powerful storm in as many weeks was bearing down on a string of battered Caribbean islands, with forecasters saying that Maria had strengthened into a hurricane on Sunday and would intensify before hitting the Leeward Islands on Monday night.
Maria continued to strengthen as it approached the Lesser Antilles, the U.S. National Hurricane Center said, estimating its winds at 80 miles per hour (130 kph).
"Additional strengthening is forecast during the next 48 hours, and Maria could be near major hurricane intensity when it moves across the Leeward Islands Monday night," the forecaster said.
Maria is approaching the eastern Caribbean less than two weeks after Irma hammered the region before overrunning Florida. That storm, one of the most powerful ever recorded in the Atlantic with winds up to 185 miles per hour (298 kph), killed at least 84 people, more than half of them in the Caribbean.
Hurricane conditions were expected for Guadeloupe, Dominica, Martinique and St. Kitts, Nevis and Montserrat, and the hurricane center warned Puerto Rico to monitor the storm.
The government of Puerto Rico has already begun preparations for Maria, which by Tuesday was expected to unleash powerful winds on the U.S. territory, already dealing with a weakened economy and fragile power grid.
Damage to Puerto Rico could also disrupt the disaster relief supply chain to other islands that were hit by Hurricane Irma two weeks ago.
"Puerto Rico is our lifeline," said Judson Burdon, a permanent resident of Anguilla who has helped coordinate supply shipments to the island. "We had two volunteer flights cancel because of the weather that is coming."
The planned deliveries consisted of plywood, power tools and screws to close up windows and doors that remain open on the island, where 90 percent of structures were damaged.
As of 8 p.m. (0000 GMT), the center of the storm was about 125 miles (200 km) east-northeast of Barbados and about 255 miles (410 km) east-southeast of the Leeward island of Dominica.
The hurricane center also issued a tropical storm watch for portions of the U.S. mid-Atlantic and New England coast by Tuesday as a second hurricane, Jose, moved slowly north from its position in the Atlantic Ocean about 315 miles (510 km) southeast of Cape Hatteras, North Carolina.
The eye of Jose, with top sustained winds of 90 miles per hour (150 kph), should remain off the U.S. East Coast, the NHS said.
Even so, by Tuesday it could bring tropical storm conditions from Fenwick Island, Delaware, to Sandy Hook, New Jersey, and from East Rockaway Inlet on New York's Long Island to the Massachusetts island of Nantucket.
Up to five inches (13 cm) of rain could fall over parts of the area, and the storm could bring dangerous surf and rip currents as well. (Reporting by Frank McGurty and Jessica Resnick-Ault; Editing by Daniel Trotta and Mary Milliken)