It's one of a number of fast-moving fires across the New England North West in recent days which has firefighters on high alert, despite the soaking rains.

The bushfire danger period kicked off on Saturday, and the RFS is on notice for a dangerous season with extra grass growth fuelling the fire from back-to-back La Nina rain events.

By Monday, the Limestone fire had burnt through more than 127 hectares of land in the Ashford area, near the Kwianbal National Park, north of Inverell.

Four aircraft including water bombing helicopters and fixed wing planes had to be deployed over the weekend to fight the huge blaze after it took hold late on Friday.

On Monday, a spokesperson for the RFS told the Leader a brigade was still on the ground mopping up hot spots and patrolling for reignitions, but it was under control.

The spokeswoman said the the remote fire took off and "brigades were only able to gain access to the eastern side and the fire spread to the west".

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"Access by ground was not possible so we were using aircraft to control the fire at that point," she said.

While the fire didn't threaten any properties, it was fast moving and firefighters raced to stop it from spreading towards properties, and into the nearby national park.

"The cause and origin of the fire is under investigation," the spokeswoman said.

On Monday, three trucks were deployed to fight a haystack fire which took hold in a paddock off the Oxley Highway near Coonabarabran.

The emergency call was made at 10.55am after a grassfire took off, burning 10 hectares of land with hay stacks in the paddock.

Access to the fire was "providing to be difficult" for crews, the spokeswoman said, "because of boggy ground".

Late last week, the Narrabri RFS deployed three trucks to help several other firefighting crews to douse a fast moving grassfire in the foothills of Kaputar National Park.

The RFS, together with National Parks and Wildlife crews, managed to contain the blaze before it spiralled out of control.

"Even with the current rain events and high moisture content, the fire moved rapidly as grass fires do and burnt out several acres," the RFS said.

"This is a timely reminder as we enter the bushfire danger period not to become complacent."

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