Hardware giant Bunnings has been left red-faced after being caught selling a declared weed as a garden plant to customers in the Northern Territory .

The NT Environment Department issued an urgent plant recall after learning the invasive weed sagittaria was accidentally sold to Bunnings customers in Darwin and Palmerston.

The department said at least 27 pots of sagittaria were sold after they were incorrectly labelled as melon sword by a Top End wholesaler.

Sagittaria is a fast growing perennial aquatic plant native to North America that is considered a threat to waterways and wetlands across Western Australia and is not known to grow in the NT.

It is common in other parts of Australia.

'Incorrect supplier labelling'

Responding to the incident, Bunnings said it sold the plants due to incorrect supplier labelling.

"As soon as it was brought to our attention, we moved swiftly to immediately isolate the plants from sale and notified the supplier of the labelling error," Bunnings chief operating officer Clive Duncan said in a statement.

"We take this matter extremely seriously and an investigation with the supplier is currently underway."

Bunnings repeat offender in selling weeds

It is not the first time the hardware giant has been caught selling weeds to customers.

In 2010 the retailer was fined $15,000 for selling the noxious weed Mexican feather grass and, according to Australian Associated Press, then took steps to ensure it would never again sell noxious weeds.

The department has urged anyone who bought the plants between August 12 and September 9 to contact the weed management branch.

Fines may apply for not returning the weeds.