Two men and two women have been charged after allegedly tampering with a race at Cobram on June 22, 2015.

The arrests come after Fairfax Media exclusively revealed in August last year that detectives had arrested four harness racing industry participants at the Breeders Crown at TAB Park in Melton. The event is one of the biggest harness meets in Australia.

On Wednesday, police said four people had been charged in relation to race fixing.

"A 30-year-old man and a 22-year-old woman both from NSW and a 22-year-old woman and 22-year-old man both from Shepparton have been charged with engaging in conduct that corrupts a betting outcome and other related offences," a police spokeswoman said.

They have been summoned to face Shepparton Magistrates Court on February 20.

The police investigation centred on the 2015 Cobram race, which was won by a horse called Airbourne Magic, trained by David Bartley. Bartley is not alleged to have been involved in fixing.

Champion reinsman Nathan Jack ran third in the race on Tooram Lad, ahead of the favourite Dehillman.

The investigation began after Harness Racing Victoria reported suspicious activity to police.

"Victoria Police maintains close relations with HRV and other key industry partners in order to monitor activity, detect irregularities, and collect intelligence," the police spokeswoman said.

It is the second time in as many years Victoria Police has uncovered alleged harness race fixing in an industry that generates tens of millions of dollars in gaming revenue for the state government.

In 2015, detectives arrested and charged two leading harness racing figures - father and son team Shayne and Greg Cramp. The pair later avoided jail when they pleaded guilty to race fixing offences and were banned from the sport for 12 years.