An invasive ant species whose bite can be lethal has been found at Fremantle Port, the first time it has been detected in Western Australia, prompting concerns about the spread of the pest.

Key points: Six red imported fire ant nests were destroyed at Fremantle Port last week

Six red imported fire ant nests were destroyed at Fremantle Port last week Fire ant stings can cause death in rare cases by causing an anaphylactic reaction

Fire ant stings can cause death in rare cases by causing an anaphylactic reaction Authorities are searching areas near the port for any further signs of the pest

The red imported fire ant is considered one of the world's worst invasive ant species, as it can form super colonies with multiple queens that develop extensively and spread quickly.

Six nests were found at Fremantle Port last week and destroyed by the Department of Primary Industries and Regional Development.

Authorities are now surveying the port and nearby surroundings for any further signs of the pest.

Agriculture Minister Alannah MacTiernan said she was hopeful the nests had been destroyed early enough to prevent the further spread of the pest.

Port workers and Fremantle residents have been urged to look out for the ants. ( Supplied: Department of Primary Industries )

"We do have pretty rigorous detection regimes but unfortunately ants are small and they can evade detection," Ms MacTiernan said.

"We are now looking at where containers have gone and going out and doing those inspections of the container terminals, but this is a pest that we really need everyone to take very, very seriously."

Fire ant bites potentially lethal

Ms MacTiernan said the ants could inflict a painful, fiery sting, which in rare cases could cause a severe acute reaction.

In rare cases, the ant's sting can cause death from anaphylactic shock. ( Supplied: Department of Agriculture )

"There have been people who have been killed, there are a number of individuals who have an anaphylactic reaction to it," she said.

"It's definitely caused deaths and it has caused lots of people to become quite ill, so it is really quite a serious pest.

""When it bites human beings it causes the body to react like it is on fire.

"It is also a major problem for horticulture, it really invades the stems and roots of plants and it massively drives down productivity of those crops.

"It can also create situations where people just simply cannot use outside places, cannot picnic or play outside because the consequences of being exposed to the fire ant are so problematic."

Ants likely from overseas, not Queensland

Ms MacTiernan said the species had been a problem in Queensland for some time, but the ants found in Fremantle were believed to have been transported by one of WA's international trading partners.

Agriculture Minister Alannah MacTiernan says she hopes they have stopped the pest from spreading. ( ABC News: Alisha O'Flaherty )

"We have got pretty good insight into the genetics of the red imported fire ant that has taken root in Queensland and we are confident that this is not genetically related," she said.

"So the conclusion that we draw from that then is that this has come from overseas."

Authorities are checking Fremantle Port and nearby surroundings for any other signs of the pest. ( Supplied: Qld Department of Agriculture and Fisheries )

Fremantle Port workers, local residents and businesses are being asked to alert authorities to any unfamiliar ants in the area.

The red imported fire ant looks similar to common native ants, with a reddish-brown colour and a length between 2 to 6 millimetres.