Hurricane Rita threatens Gulf coast

Hurricane Rita is expected to strengthen to a powerful Category 4 storm as it heads towards the ravaged US Gulf coast.

Louisiana residents have been urged to flee for the second time this month amid fears the storm could shatter levees wrecked by Hurricane Katrina.

Thousands of residents and tourists fled the Florida Keys as Rita lashed the islands with heavy rain and strong winds.

The storm has already been upgraded to a Category 3, rapidly gaining force as it heads across the Gulf of Mexico.

If it veers east and strikes Louisiana the effects could be devastating.

State officials said they were taking "extraordinary precautions" as they warned that weakened levees would not cope with another battering.

Rita is the ninth hurricane to form in the Atlantic this season and has already brought heavy rains and flooding to Cuba.

The National Hurricane Centre said it was likely to hit Texas on Friday or early Saturday.

A mandatory evacuation order has been called in Galveston, Texas while the state's National Guard troops have been recalled from the Katrina relief effort in Louisiana, Sky News reports.

Photo: the AP