Fake Australian $100 notes supposed to be used to train Chinese bank tellers have made their way to Darwin where people are using them illegally.

Northern Territory Police have warned people to look for the notes, which are marked with Chinese characters that reportedly translate as "Training Money. SAMPLE. Only for practice. Circulation Forbidden".

The notes, along with other denominations have been sold via online store eBay, with disclaimers from the sellers they are not to be used as real currency.

A description on one of the advertisements read: "The colours on the notes are very close — close enough to make me do a double take every time my daughter leaves some lying around."

Used to buy cigarettes, alcohol

In the past two days there have been seven reported cases of the counterfeit notes being used at businesses in Darwin, mainly to buy cigarettes and alcohol at bottle shops, Detective Senior Sergeant Glenn Leafe said.

He said that while the notes are marked with Chinese characters and obviously fake, they can be easily mistaken for real currency when they are rolled or folded.

"These notes are the kind that are available quite commonly over eBay," Detective Senior Sergeant Leafe said.

"They are training notes. They're not a counterfeit currency so to speak but they are something that can be used to deceive store owners."

Mr Leafe said most of the incidents involved a man and a woman using the notes before collecting change and quickly leaving the scene.

Check your notes, police urge

It has been alleged the pair attended a licenced premises in the Darwin suburb of Marrara and attempted to exchange a counterfeit note for goods, but after being challenged by staff they fled the store.

Police have urged people to check whether any $100 notes they receive are genuine and have published a photo of the imitation note on social media.

They have called on anyone who has a fake note, or information about them, to contact police.

Fake US $50 notes with the same Chinese writing have emerged in America in the past.