Houston - Hurricane Ike made landfall early Saturday lashing the barrier island of Galveston near Houston with winds over over 170 kilometres an hour, and flooding vast tracts of low land.

There were fears for around a third of the 60,000 residents who ignored strict orders to evacuate as the National Hurricane Center reported the storm's eye making landfall just after 0700 GMT.

There were warnings of "potentially catastrophic" flooding and wind damage on the island, which a century ago saw the deadliest hurricane ever to hit the United States, killing an estimated 8,000 people.

After issuing the sternest of warnings to evacuate, authorities were initially ignoring any calls for rescue until daybreak when, according to Galvestion Mayor Lynda Ann Thomas, "we don't know what we are going to find. We hope we will find the people who are left here alive and well."

Up to 100,000 homes in the entire Houston region bracing for the worst were expected to be flooded, and hundreds of buses were on standby to help rescue and evacuation work.

Large portions of Galveston were already flooded earlier Friday. Residents in one or two-story buildings were ordered to leave or else face "certain death" from likely eight-metre storm surge flooding.

The strong category-two storm on the five-level Saffir-Simpson scale could still strengthen into a category three before the storm's centre reaches land, the National Hurricane Centre in Miami said.

The storm had sustained winds of 175 kilometres per hour - just shy of a category three storm. Winds were as much as 48 kilometres per hour stronger on high buildings, the centre said.

The gravest problem was however the tidal surge created by the hurricane. Owing to its large diameter, meteorologists compared its effects to that of a category 5 hurricane.

Despite several warnings and a mandatory evacuation order issued Thursday, many residents in Galveston decided to stay and weather the storm at home.

Many considered exaggerated the official announcements, thought their homes were strong enough or rejected risking a chaotic evacuation like that of hurricane Rita in 2005. A few also mentioned a wish to live through the storm at its worst.

Galveston is known for its nearly 6-metre-high seawall built to protect historic old homes which survived the lethal storm of 1900.

In 1900, up to 8,000 people died after a huge hurricane hit Galveston, causing the deadliest natural disaster in US history. In 2005, Hurricane Katrina killed about 1,800 people in New Orleans and the surrounding Gulf coast.

Police and firefighters made their final sweep through Galveston early Friday evening with a large dump truck to pick up any hold-outs willing to leave.

The US Coast Guard performed nearly a hundred successful rescues, but helicopters were soon grounded as hurricane winds picked up.

The lethal hurricane is bearing down on the Texas and Louisiana coasts from west of New Orleans to Corpus Christi, near the Mexican border, sending 1.2 million people fleeing for safety, Texas Governor Rick Perry said.

The eye of the storm was expected to hit Houston early Saturday. The city is the country's fourth largest with 4 million people and home to 15 per cent of the country's petrochemical industry, Perry noted.

US President George W Bush sent an urgent appeal to stubborn residents who refused to evacuate, urging "fellow Texans to listen to what authorities are saying."

From Houston alone, 250,000 people directly in the storm surge path were evacuated. In addition, 12,500 seriously ill or elderly people were moved to safety, Perry said.

Utility officials are bracing for power outages that could affect more than 5 million people and last "for weeks", and the Federal Emergency Management Agency anticipated 100,000 homes would be flooded.

"It is a potentially catastrophic hurricane," Homeland Security Secretary Michael Chertoff said in Washington. "We will move as swiftly as possible to relieve suffering."

Ike has already killed at least 72 people in Haiti and five people in Cuba as it churned across the warm Gulf waters since last weekend.