An eerie, smoky haze is settling over the remote Northern Territory town of Tennant Creek as a mega-blaze four times the size of the ACT looms.

The major fire remained at a “watch and act” level late on Monday as it continued to burn east of Tennant Creek.

The blaze has closed the Barkly Highway multiple times over the past few days and has burnt more than 9000 square kilometres under “high to extreme weather” conditions.

Bushfires NT said the level of risk to the township is heightened, and containment strategies are “not in place for the entire perimeter”.

The Australian Defence Force has also moved into Tennant Creek to help firefighting efforts.

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Barkly Arts Centre worker Kitty Tunnell said an “eerie” feeling had settled into the town.

“There is smoke drifting through the town and a dense band of grey smoke on the horizon,” she said.

A health alert is in place and Ms Tunnell said locals had sore throats and were coughing.

A smaller fire, disconnected from the Barkly blaze, burning closer to town on Sunday had been mostly put out by Monday morning.

The small blaze was under control though authorities were doorknocking on Sunday night to warn residents of the looming Barkly fire.

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Deputy Chief Fire Officer Joshua Fischer told ABC Radio the blaze could put homes at risk.

“What we’ve learned with this fire and how it’s behaved over the course of it, there is a real risk in the next 24 hours that this fire may impact upon Tennant Creek,” he said on Monday.

Mr Fischer said there had been reports from Tennant Creek of the fire’s distant glow, worrying authorities about the fast-moving blaze.

It’s not known whether the fire has jumped the Gosse River, though authorities on the south-east of the town have been doorknocking, with aircraft on stand-by in Tennant Creek.

“The last few nights we’ve seen the fire make really impressive runs and I don’t mean impressive in a good way,” Mr Fischer said.

“Impressive runs where it’s travelled 50 to 60 kilometres overnight.”

Motorists told AAP flames from the front could be seen from the Stuart Highway en route to Darwin.

“It is certainly a warning of what is likely to come as we move through the summer period in central Australia,” Mr Fischer said.

-AAP