Firefighters in far western New South Wales are frustrated by a bizarre blaze that has been burning on and off for weeks under a dry lake.

About two months ago crews were called out to Lake Woytchugga, about five to 10 kilometres west of Wilcannia.

Chris Favelle, who manages the Rural Fire Service's far west team, said the sight that greeted them was certainly curious.

"We just got a call to the lake and sent our brigade as we normally do," he said.

"I think they were fairly perturbed to find that it appeared that the lake edge was on fire."

Since then, firefighters have tried digging up the hot ground and flooding it, but the smoke keeps coming back.

They suspect it could be being fuelled by ancient organic matter that just keeps smouldering.

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"It's a lake bed that's only got water in it after floods and those sorts of things," Mr Favelle said.

"So we've tried everything from flooding the area with water, taking water tankers in and just flooding it, through to trying to dig a breaker around the area and contain the fire within a set location.

"Lately we've tried actually digging up the hot ground and trying to extinguish it that way but it just seems to keep going on us at this point in time."

It is proving to be one of the most frustrating fires they have had to fight.

"It's very uncommon. I've worked for the Rural Fire Service now for probably 15 years or so and never seen anything like this," Mr Favelle said.

"Of course it's very difficult to deal with at the moment, that's for sure.

"If you would imagine that there is an organic matter under the surface and it's mixed in with sand and other sorts of things on the edge of the lake, and as it heats up through the day it just, smoke just emanates from the ground, basically.

"What we're concerned about is that it doesn't get into grass and other things that are on the edge and get away from where it is really confined to at the moment."

The Rural Fire Service does not know for sure how the blaze started, but Mr Favelle suggested it could have been sparked by someone's campfire on the edge of the lake bed.

"[There is] probably nothing untoward about it at all. It's just got into this material and once it's got going, yeah, very difficult to deal with," he said.

"On a cool day and with no wind around you don't really see it.

"It's below the surface of the lake edge I guess. It's only when the wind comes up and there's a bit of heat though the day that... [a] little bit of smoke emanates from the ground."