(Adds BHP mine stop, flights cancelled, detail of evacuations)
By Tom Westbrook
SYDNEY, March 27 (Reuters) - Thousands of Australians abandoned their homes as a powerful cyclone bore down on coastal towns in Queensland on Monday, while others ignored authorities' advice to evacuate with winds forecast to reach up to 300 km per hour (185 mph).
Cyclone Debbie is a forecast to strengthen to a Category four storm before it makes landfall in the northeast state early on Tuesday, the Australian Bureau of Meteorology said.
State Premier Annastacia Palaszczuk warned it would be the most powerful storm to hit the country since Cyclone Yasi in 2011, which destroyed homes, shredded crops and devastated island resorts.
About 3,500 people left low-lying townships near Townsville, while authorities advised 2,000 more people in the town of Bowen to also leave, Palaszczuk said, adding that the "window of opportunity to leave is drastically closing" as weather worsens.
"This is going to be a nasty cyclone," Palaszczuk told Nine Network television. "These wind gusts are going to be absolutely huge."
A category five storm is the strongest on the five-step Saffir-Simpson scale of hurricane intensity.
The Abbot Point coal terminal and ports at Mackay and Hay Point were closed until further notice, ports spokeswoman Fiona Cunningham said.
BHP Billiton BHP.AX BLT.L suspended operations at its South Walker Creek coal mine, which is just to the south of the cyclone's expected path. were already lashing the tourist resorts at Airlie Beach and the Whitsunday Islands.
Townsville Airport was closed and airlines Qantas QAN.AX , Jetstar, Rex and Virgin Australia VAH.AX said they had cancelled several flights to and from the region scheduled for Monday and Tuesday.
Pictures showed residents who had stayed behind protecting homes and shops with sandbags and plywood boards.
"We'll just give it a go and rally together," Cungulla resident Mike Kennedy told the Australian Broadcasting Corporation.
Queensland produces some 95 percent of Australian bananas and while Cyclone Debbie is on course to miss the largest growing regions in the state's far north, analysts said heavy rains and strong winds could cause significant crop damage.
The cyclone is expected to miss most of region's coal mines, weather and mining data in Thomson Reuters Eikon shows, and no major dry-bulk vessels are in storm's path. blamed the wild weather associated with the storm for a traffic accident in which a 31-year-old female tourist died. Police did not give the woman's nationality.