An elderly man scammed out of $20,000 got his cash back in a last-minute airport search thanks to fast action by police in Gore.

The man came into Gore Police Station speaking in code and talking about corruption between local police and a Gore bank.

He asked to check a police ID number, saying he needed the information for a detective overseas he was helping with an investigation into counterfeit cash.

Sergeant Eric Browne said after he managed to convince the man the overseas detective did not exist, he opened up about the details of his strange experience.

The man had received a phone call from someone claiming to be a police officer investigating counterfeit currency being produced by the Gore bank the man uses.

The fake detective asked the man to read out serial numbers from cash he had with him, then informed him his notes were counterfeit.

The scammer told the man to withdraw cash, put the bills within the pages of books, and courier them to a London address. He was told this would give investigators a good sample to check for counterfeiting.

The man had done what was asked and had sent the books the previous day.

"Alarm bells were well and truly going off in my mind at this point," Sergeant Browne said. "And when he told me he had withdrawn $20,000, I knew we had a significant scam on our hands."

The sergeant swung into action to try to retrieve the parcel.

"We had to act fast, so I immediately got his tracking number, saw that it would be going out through Auckland International Airport and reached out to the International Mail Centre there.

"It turns out the boss there was a detective for 30 years, and he assured me he would do all he could to get this package, but it really was going to be a close call to catch it in time."

There were three cargo crates going onto the plane the man's package could have been in.

"The first two had been loaded on already, and with a last-ditch search in the third crate, this man's package was found right at the very bottom," Sergeant Browne said. "It was like something out of a Hollywood script."

The man will get his money back, and police are investigating the overseas address to try to prosecute the scammers.

Main image (Supplied/NZ Police): One of the books the elderly man hid cash in before sending it to London.