A US Navy reserve hurricane hunter plane that flew into the monstrous weather system late Monday recorded maximum sustained winds of 256 kilometers (160 miles) per hour, with higher gusts.

That makes Dean "a potentially catastrophic category five hurricane on the Saffir-Simpson hurricane scale," the Miami-based US National Weather Center said.

Since record keeping started in 1886, only 28 Atlantic hurricanes are known to have reached that intensity.

Late Monday, the outer bands of the storm started hitting Mexico's Yucatan Peninsula, which braced for the full fury the hurricane was expected to unleash when it barrels ashore.

The storm already killed at least nine people across the Caribbean.

Authorities nonetheless heaved a sigh of relief as forecasters said Cancun and other popular tourist destinations along Mexico's Caribbean coast would likely be spared a direct hit, with Dean expected to make landfall in a less populated area further south.

But fears the usually crowded resorts could be battered by huge waves and flooded by storm surge, led to the evacuation of thousands of tourists.

Authorities also deployed about 1,000 police officers to prevent the type of looting that followed the devastation wrought by Wilma, a category five hurricane that killed 10 people and left millions of dollars in damages in Cancun two years ago.

Projections had Dean hitting land about halfway between Cancun and Chetumal, 300 kilometers (186 miles) away, on the border with Belize.

Most of the Yucatan Peninsula's coastline was placed under a hurricane warning, as were all the coastal areas and islands of neighboring Belize, a central American country popular with divers for its barrier reef.

State-run Petroleos de Mexico (PEMEX) said it evacuated and shut down all its offshore oil installations in the Gulf of Mexico.

While rigs on the US side of the Gulf did not appear directly threatened, 10 of the 834 manned production platforms and 24 of the 101 rigs were evacuated, according to the government's Mineral Management Service.

Forecasters said the storm was expected to lose some of its strength as it crosses the Yucatan Peninsula on Tuesday, but could regain major hurricane status as it barrels over the warm Gulf of Mexico waters on the way to a second landfall later in the week in northern Mexico.

World oil prices dropped on Monday as forecasters indicated the hurricane appeared likely to spare energy facilities in the United States, the world's biggest consumer of crude.

At midnight GMT Tuesday, the hurricane raged 335 kilometers (210 miles) east of Chetumal.

In Jamaica, where one man died when his house caved in on him, residents began a massive clean-up one day after Dean toppled trees and power lines and flooded low-lying areas.

Prime Minister Portia Simpson Miller announced security forces would be granted wider powers following reports of looting across the island that remained largely without power on Monday.

But Jamaica was spared the worst of Dean's massive punch as the storm's powerful inner wall brushed just past the island.

Hurricane Dean earlier swirled past Haiti, one of the world's poorest countries, lashing it with heavy rain and gale-force winds and leaving at least four people dead.

Two people were also killed in the French territory of Martinique and another two died in the Dominican Republic, while thousands of people across the region fled their homes.