Scammers pretending to be from the foreign affairs and immigration departments are targeting migrants who recently returned to Australia, the Australian Competition and Consumer Commission said.

Victims are being told that they gave false information on their visa or departure documents when they returned home and must hand themselves into police or pay a $1000 fine via Western Union wire transfer to avoid being deported.

The scam appears to be capitalising on unease over changes to citizenship laws and the overhaul of the controversial 457 visa program.

Scamwatch has received more than 20 reports this month, with at least five people handing over personal information and paying more than $6,200 in total.

The ACCC said the scam, which is targeting migrants who have recently returned from India, seems legitimate because the phone number that appears as the caller ID is a genuine Department of Foreign Affairs and Trade number.

It is believed the scammers are using a device that masks their number and replaces it with another.

Deputy chair Delia Rickard said people should hang up the phone if they receive a call from a person claiming to be from a government agency who makes threats or demands money

"If you have any doubts about someone who says they are from a government department, contact the department directly," she said. "Don't use any phone numbers, email addresses or websites provided by the caller - find these details through an independent source such as a phone book or online search.

"Don't trust the caller ID as this can be faked."

Government departments will never ask for wire transfers.