The Bureau of Meteorology said low visibility had been reported in some areas around the defence firing range at Port Wakefield, north of Adelaide. It said lingering smoke from the seaweed was being trapped in the lower atmosphere by a temperature inversion.

The fire was sparked today and was quickly brought under control without posing a risk to any property.

The Country Fire Service (CFS) said it was contained to an area of the defence department's Port Wakefield Proof Range. Earth breaks had been established around the blaze, which was being monitored by defence personnel.

A CFS spokesman said it would be allowed to burn itself out. CFS crews were not in attendance as the location was not a threat to property or lives and could not spread.

Regional duty officer Andy Warner said members of the public should not be concerned by the smoke but were advised to close doors and windows until it passed.

"Those travelling in the area should exercise caution as smoke may reduce visibility," he said.

"People with respiratory problems are advised to stay inside and close all doors and windows until the smoke has passed."

Its cause had not been determined.