Hurricane Ida roared through the Gulf of Mexico on Sunday, where important oil fields are located, after triggering floods and mudslides that killed 124 people in El Salvador.

Ida swept past the Mexican resort of Cancun, doing little damage to the city, and was expected to weaken gradually on Monday as it heads toward some of the oil and gas production facilities in the central Gulf, the US National Hurricane Center said.

The storm reached hurricane force again late on Saturday and strengthened to a Category 2 storm on Sunday with sustained winds of near 105 mph (165 kph), the Miami-based hurricane center said in its 4 pm EST (2100 GMT) advisory.

Some energy companies in the Gulf of Mexico were evacuating workers from offshore platforms and at least two large producers -- BP and Marathon Oil Corp -- shut down some oil and gas production as a precautionary measure. Other companies were preparing for possible shutdowns.

The Louisiana Offshore Oil Port, the only terminal in the US capable of handling the largest tankers, said it would stop unloading ships due to stormy seas.

A quarter of US oil and 15 percent of its natural gas are produced from fields in the Gulf and the coast is home to 40 per cent of the nation's refining capacity.

The hurricane center set a hurricane watch from Grand Isle, Louisiana, to Mexico Beach in northwestern Florida, but did not include the city of New Orleans. A hurricane watch means hurricane conditions are expected in the area within 36 hours.

Louisiana Governor Bobby Jindal declared a state of emergency on Sunday, allowing the government to mobilize troops and rescue workers.

If Ida makes landfall in Louisiana it would be the first storm to strike the state since Hurricane Gustav came ashore in September 2008.

In El Salvador, rivers burst their banks and hillsides collapsed under relentless rains triggered by Ida's passage, cutting off parts of the mountainous interior from the rest of the country.

El Salvador's government said 124 people were killed as mudslides and floods crushed homes and swept away rudimentary houses.

The bulk of the Central American country's coffee is grown in areas far from the worst affects of the flooding but the national coffee association had no estimate of potential damage to the harvest.

As of 7 pm EST (0000 GMT), Ida was 445 miles (720 km) south-southeast of the mouth of the Mississippi river, the hurricane center said. It was moving north-northwest near 12 mph (19 kph) and was forecast to turn toward the north over the next two days. - Reuters