KINGSTON (Reuters) - Tropical Storm Gustav hit Jamaica with near hurricane-force winds on Thursday after killing at least 59 people elsewhere in the Caribbean, and was on a path to reach New Orleans and the Gulf of Mexico oil fields as potentially a powerful hurricane.

As Gustav churned through the Caribbean, Tropical Storm Hanna formed in the Atlantic Ocean with 40-mph (65-kph) winds and took a track that could threaten the Bahamas and Florida, also next week, the U.S. National Hurricane Center said.

Energy companies prepared for Gustav to deliver what could be the hardest hit to the heart of the U.S. Gulf oil patch since the devastating 2005 hurricane season.

Oil prices rose above $120 a barrel in early trade on Thursday, adding to two days of gains as Gustav aimed deep into the heavy concentration of oil and natural gas platforms off Louisiana and Texas.

But crude price fell back more than $2 after the U.S. government and the International Energy Agency pledged to release emergency stockpiles if Gustav disrupts production in an area that provides the United States with a quarter of its crude oil and 15 percent of its natural gas.

The seventh storm of a busy Atlantic hurricane season was 15 miles east-northeast of Kingston, Jamaica, at 5 p.m. EDT (2100 GMT), the hurricane center said. Its top sustained winds were 70 mph (110 kph), just short of the 74-mph (119 kph) hurricane threshold. Forecasters said it could become a hurricane by Friday.

POSSIBLE EVACUATIONS

New Orleans, the southern U.S. city ravaged by Hurricane Katrina three years ago, remained near the middle of the range of possible landfall locations on the U.S. Gulf Coast.

Louisiana Gov. Bobby Jindal put New Orleans residents on alert for possible evacuations from Friday, the third anniversary of Katrina’s strike, and issued a precautionary disaster declaration. A state of emergency was declared in neighboring Mississippi, which was also devastated by Katrina.

In Jamaica, shops, post offices and schools shut their doors and authorities ordered nonessential workers to stay home as Gustav neared and began buffeting the lush, mountainous island with high winds and torrential rains that soaked some sugar cane fields.

“I just saw part of my roof blow away,” said Phillip Wright, resident of an eastern parish where extensive damage to some homes was reported.

“This looks very serious. It is windy, rainy, trees are also falling down and we have no electricity,” Wright told Reuters by telephone.

Gustav barged ashore as a hurricane in Haiti on Tuesday and its driving rains killed at least 59 people there and in the neighboring Dominican Republic.

Slideshow ( 14 images )

“There are 51 people killed,” Alta Jean-Baptiste, director of Haiti’s civil protection office, told Reuters on Thursday. She said the deaths occurred primarily as a result of flooding and mudslides in western and southern Haiti.

GAPS REMAIN

Gustav is the first serious Atlantic storm since the 2005 hurricane season to threaten New Orleans and the 4,000 U.S. energy platforms in the Gulf.

Slideshow ( 14 images )

Katrina and Rita destroyed 124 platforms and severed pipelines when they swept through as Category 5 storms. Katrina came ashore near New Orleans on August 29, 2005, as a Category 3 hurricane and flooded the city. It killed 1,500 people along the Gulf Coast and caused $80 billion in damage.

U.S. Army Corps of Engineers program manager Bill Irwin told a news conference on Thursday that gaps remain in New Orlean’s flood control system and that it is still vulnerable despite improvements made after Katrina.

The agency was rushing to install temporary flood-prevention structures, Irwin said.

Energy companies shut down production and pulled workers from Gulf offshore rigs. The Louisiana Offshore Oil Port, the nation’s only deepwater oil port which normally offloads about 1 million barrels of foreign crude per day, expected to stop working over the weekend.

On its current path Gustav will threaten the Cayman Islands and western Cuba before entering the Gulf.

Energy traders also warily watched newborn Hanna, 260 miles

northeast of the northern Leeward Islands. The storm was moving west-northwest at 12 mph (19 kph) and could become a hurricane by next week.