A fire in Wither Hills near Blenheim that brought back memories of a devastating blaze in 2000 was "started by a human action", firefighters say.
The fire started close to a public walkway in Wither Hills Farm Park and the council-owned park is closed until further notice.
A fire on Boxing Day, 2000, swept through 7000ha of Marlborough pasture and reports on that fire said it started near the walkway entrance to the same park.
A swift response by urban and rural fire fighters, including four helicopters with monsoon buckets, prevented a repeat of the Boxing Day fire, says Richard McNamara, the Marlborough Kaikoura Rural Fire Authority principal fire officer.
The latest fire is under control and a forensic fire investigator is at the scene.
It was a very serious situation because conditions were dry and the park had steep slopes, Mr McNamara said.
"This fire has been started by human action. Anyone with information is asked to contact the police," he says.
"Fire is a very serious scenario in this park, not least because this is a very popular area for walkers and bikers and there can be hundreds of people in the area during the weekend," he said.
The Blenheim Urban Brigade held the fire to the lower flanks until rural crews arrived.
By chance, a rural fire training exercise was under way at the nearby Woodbourne RNZAF Base and 16 firefighters were immediately sent from there to the fire.
"That gave us a lot of hitting power early on and it has made the difference," Mr McNamara said.
Ground crews will continue to dampen down the area today and one crew will patrol the area overnight in case the fire reignites. Two helicopters remain on standby.
About five hectares of land has burnt.