'Aggressive' red ants found at Sydney port

A species of "highly aggressive" Argentinian ants which can give a painful sting have been found at Sydney's Port Botany.

The outbreak of red fire ants has been described as "serious" with emergency management, biosecurity and plant and pest insect specialists attempting to eradicate the insects.

"Red imported fire ants are a nasty pest; able to inflict painful stings on people, pets and livestock," NSW Primary Industries Minister Katrina Hodgkinson said.

Fire ants are reddish-brown in colour and range from 2mm to 6mm in length.

They have also been found in Queensland, with eradication efforts there already amounting to $281 million since 2001.

"Entomologists are continuing to conduct surveillance on site and in the surrounding area to ensure the ants haven't spread and while a further nest was detected late last week, no additional sites have been identified," Ms Hodgkinson said.