Australia evacuated thousands of people from its northeast coast on Tuesday as a cyclone rivalling Hurricane Katrina bore down on tourism towns and rural communities, with officials saying it could even threaten areas deep inland that were ruined by floods last month.

Mines, rail lines and coal ports were closed in Queensland state as Cyclone Yasi headed towards the coast. Up to a third of Australia's sugar crop was also under threat, officials said.

This storm is huge and life threatening, Queensland Premier Anna Bligh said, warning the system was intensifying and picking up speed on its path from the Coral Sea, with destructive winds expected from Wednesday morning.

Cyclone Yasi is expected to generate winds of up to 280 kph (175 mph) and bring heavy rain when it hits the northern coast of tropical Queensland state late on Wednesday, matching the strength of Katrina, which devastated New Orleans in 2005.

The Bureau of Meteorology upgraded Yasi to a category four storm on Tuesday evening and said its very destructive winds would pose a serious threat. Sea levels would rise significantly as it crossed the coast, the bureau said on its Website.

With a strong monsoon feeding Yasi's 650 km (400 mile) wide front, the storm was also expected to maintain its intensity long after smashing into the coast and could sweep inland as far as the outback mining city of Mt Isa, 900 km (600 miles) inland.

More than 400,000 people live in the cyclone's expected path, which includes the cities of Cairns, Townsville and Mackay, which are also main tourist areas and take in Australia's Great Barrier Reef.

The military was evacuating nearly 40,000 people from low-lying coastal areas overnight on Tuesday, officials said.

Queensland, which accounts for about a fifth of Australia's economy and 90 percent of steelmaking coal exports worth about $20 billion a year, has had a cruel summer, with floods sweeping the eastern seaboard over the past month, killing 35 people.

There's no time for complacency, said Mike Brunker, mayor of the Whitsunday area near the Great Barrier Reef. People in low-lying areas are evacuating to friends and family or, if they have to, leave town.

Island resorts in the Whitsundays and parts of the tourism hub of Cairns and Townsville were being evacuated along with other areas in the danger zone, between Cooktown in the north and near Mackay, a port, further south.

The weather was calm in Townsville late on Tuesday as scores of people milled around at its airport trying to get out.

It's crazy in the shops. People are nearly killing themselves to get food and water before this thing hits, said Tracy Gibbons, standing in a queue at a car rental desk.

Satellite radar images showed Yasi as a massive storm covering almost the entire Coral Sea and moving towards Australia from near Vanuatu.

Authorities said it could be the most destructive cyclone to hit the area. They hope the cyclone will cross the coast at low tide, limiting the impact of tidal flooding.

A sugar industry official said it could threaten about a third of the state's sugar cane crop.

COAL INDUSTRY ON ALERT -- AGAIN

Military aircraft were helping with the evacuation and extra commercial flights were scheduled. Police were empowered to forcibly move people from danger zones.

This is not a system that's going to cross the coast and rapidly weaken out, said Bureau of Meteorology senior forecaster Gordon Banks said. We could see this system pushing well in across northern Queensland.

Queensland's coal industry, only just recovering from the floods, went back on alert on Tuesday, with at least one major mine closing down temporarily and rail operations suspended as the industry braced for the storm.

The country's largest coal freight company, QR National, temporarily closed two rail networks: the major Goonyella network, feeding into the export terminals of Dalrymple Bay and Hay Point, and its smaller Newlands line taking coal to Abbot Point, a company spokesman said.

Global miner Rio Tinto shut its Hail Creek coal mine with the approach of the cyclone.

Queensland's coal mines are mostly inland and are still struggling to pump water out of their pits after the flooding.

The Queensland Resources Council, an industry body, estimated coal miners would take until March to return to normal, even without the impact of cyclones.

Bligh said Yasi had the potential to cause powerful and deadly flash flooding in coastal areas. Most of the state's major coal ports were temporarily closed to shipping.

But she said the storm track had shifted slightly north, meaning flood devastated and coal mining areas of central Queensland may escape the worst of cyclonic rain.

Last month's floods swamped about 30,000 homes, destroyed roads and rail lines and crippled Queensland's coal industry, with up to 15 million tonnes of exports estimated to have been delayed into the second half of this year.