Critical fire condition warnings issued across US south-west

Predicted wind gusts could cause fire to jump containment lines as crews in New Mexico try to stop growth of US's biggest wildfire

Warnings of critical fire conditions are peppered across much of the US south-west this weekend, as crews in northern New Mexico worked to stop the growth of the nation's largest active wildfire.

Two fires that merged to create the largest wildfire in New Mexico history have both been traced to planned burns set by federal forest managers as preventative measures, federal investigators have announced.