SURVEILLANCE is being extended around Yarwun to determine how far a colony of potentially life-threatening fire ants have moved.
Biosecurity Queensland officers say it is likely the ants have been at the Fisherman's Landing site for two to three years.
They have destroyed the nests found so far and completed surveillance over 1.5km around the initial detection - but will now extend the survey area up to six kilometres.
Businesses including Bechtel, Rio Tinto, Orica, Cement Australia and the Gladstone Ports Corporation haven't been ruled out as the source of the menace.
Yarwun fire ant response operations manager Gary Morton said the surveillance team was extending its program to survey an area up to six kilometres out from known fire ant infestation.
"Our main focus of this is to determine if the fire ants have travelled any further, and if so, how far they have travelled," he said.
Mr Morton called on the community to support the surveillance effort by checking their local area for unusual ants and alerting 13 25 23 if possible fire ant nests are found.