(Adds chief minister quotes, paragraphs 7-9) Australian police...

(Adds chief minister quotes, paragraphs 7-9)

Australian police ordered three nights of curfew on Monday in the outback tourist town of Alice Springs after several incidents of violence, including an alleged assault on four off-duty police officers.

Northern Territory Police Commissioner Michael Murphy said "significant harm and civil disturbances" had occurred over the last 72 hours in Alice Springs.

The officers were attacked when they were walking home and it was not immediately known if the offenders identified them as police, Murphy told reporters. The curfew will be in force from 10 p.m. to 6 a.m. local time.

Under new laws introduced in May, the police commissioner has the power to impose lockdowns for three days to control any violent incidents, and can ask the government for an extension.

"If I believe an extension is required I will put that in writing ... about the reasons why I think that should occur," he said.

A two-week youth curfew was declared in March in Alice Springs after a mass brawl involving 150 people. Community leaders have long identified alcohol abuse as a major factor behind violence.

"The offending in Alice Springs over the last few days has been unacceptable," the territory's chief minister, Eva Lawler, told a news conference on Monday.

"The curfew will provide police extra powers to get on top of the situation on the ground in Alice Springs.

"This is exactly why my government passed curfew legislation in May."

Alice Springs, a remote town in Australia's vast outback region some 2,000 km (1,243 miles) northwest of Sydney, is the gateway to major tourist attractions including the giant red sandstone monolith of Uluru, formerly known as Ayers Rock.

Around a fifth of the town's population are Indigenous Australians, who have been historically marginalised since the continent was colonised by Great Britain in the late 18th century.