One offshore gas pipeline operator said Georges had cut the flow of gas through its system in half, while two New Orleans area refineries said they were closing down until the storm passed.

The storm, with winds of 175 kph, was about 56 km south of the mouth of the Mississippi River at 2200 GMT. The National Weather Service office in Slidell, Louisiana said the eye of the storm would most likely come ashore near the Louisiana-Mississippi border around 0600 GMT.

Hurricanes or tropical storms have curtailed oil and gas production in the Gulf of Mexico in each of the last four weeks, contributing to a rise in the prices of both fuels.

The rich oil and gas fields off the coast of Louisiana and Texas normally account for about one quarter of US domestic gas production andone sixth of US domestic oil output.

Oil companies had already evacuated thousands of offshore workers late last week and some had also begun to suspend or "shut in" some of their oil and gas production after Georges pounded the Florida Keys and headed towards the Gulf.

The Tennessee Gas Pipeline Co, which brings gas ashore for numerous Gulf producers, said the volume of gas flowing through its system had fallen by about one billion cubic feet a day.

Spokeswoman Barbara Webber said this was mainly because of shut-ins by producers linked to the company's Tennessee 500 line, which has a capacity of 1.9 billion cubic feet a day.

Transcontinental Gas Pipeline Corp (Transco) said gas producers linked to its pipeline system had shut in about two billion cubic feet a day of gas production.

"We think that's the peak. We should start to see some of that production in the Mobile bay area come back on line on Monday," spokesman Chris Stockton said.

The Transco gas pipeline system in the Gulf has a carryingcapacity of 6.7 billion cubic feet a day. Among individual producers, Chevron Corp said the latest available figures showed it had shut in at least 300 million cubic feet of gas a day and 45,000 barrels a day of oil.

Chevron -- one of the biggest producers in the Gulf of Mexico with a daily output of 100,000 barrels of oil and one billion cubic feet of gas -- evacuated over 1,400 offshore workers.

Hurricane Georges also disrupted imports of crude oil to the US Gulf coast region at the weekend.

The Louisiana Offshore Oil Port (LOOP), entry point for about 10 per cent of US crude imports, said it had been forced to halt the unloading of crude oil tankers early on Saturday morning and would not resume its operations until the hurricane passed.

LOOP unloads 25 to 30 tankers a month, at its offshore terminal, 20 miles South of the Louisiana coast. The average incoming cargo is about 1.1 million barrels of crude oil.

Hurricane Georges also forced the temporary closure of at least two oil refineries in theNew Orleans area on Sunday, spokesmen for the operators said.

Shell Oil Co spokesman Don Baker said the company had decided to close down its 225,000 barrel a day refinery in Norco, Louisiana, on Sunday.

BP America spokesman Brian Summner said his company closed its 240,000 barrel a day refinery at Belle Chasse, Louisiana, on Sunday until the hurricane passed.

Officials at two other New Orleans area refineries --Mobil's 176,000 B/D Chalmette plant and Marathon's 225,000 B/D Garyville unit could not be reached for comment.