Seven people have been charged in relation to a police inquiry into allegations of race-fixing and corruption in the harness racing industry.

A 26-year-old man is due to appear in Christchurch District Court today on charges of deception by match-fixing, possessing Class B drugs for supply, and supplying Class B drugs.

Four men, aged 34, 40, 41 and 44, are due to appear in Christchurch District Court next week on match-fixing charges.

A 41-year-old woman was also due to appear the same day on two counts of supplying Class B drugs.

A 47-year-old man has been charged with deception by match-fixing and is due to appear in Palmerston North District Court next week.

The charges follow raids at 10 stables yesterday in Canterbury, Manawatu and Invercargill.

The police investigation was sparked by information passed to police by the Racing Integrity Unit as early as April last year and police have tapped phones and checked text messages as part of the investigation.

Racing Minister Winston Peters said yesterday: "This is a sad development. New Zealanders need to have confidence that the racing industry has integrity and is not above the law."

Police executed search warrants yesterday at eight properties in Christchurch, one in Manawatū and one in Invercargill.

Detective Superintendent Tim Anderson said the searches were the result of a long-running investigation into alleged corruption in the harness racing industry.

The Herald understands the investigations are into alleged race fixing involving up to four stables - with the possibility of collusion to effect the outcome of races for either gambling profit or to earn stake money.

He said the investigation began with information supplied by the Racing Integrity Unit.

"Police have been working in partnership with the RIU and other relevant organisations throughout the investigation."

The investigation was ongoing and police expected to provide further details in the coming days, Anderson said.

New Zealand Racing Board chairwoman Glenda Hughes said allegations of race-fixing were disappointing but showed "the racing integrity system is working".

"The actions taken today resulted from information received by the Racing Integrity Unit [RIU], an independent body charged with maintaining integrity in the sport," she said.

"That information initiated a co-ordinated and careful investigation between NZ Police and the RIU.

"The value of having an independent integrity body focused on investigating and prosecuting any alleged impropriety is reinforced in this action."

Racing Board CEO John Allen said: "Those involved in the industry and the Kiwi punters who support it must have confidence in the integrity of the sport.

"I am confident that our integrity systems work and that where alleged breaches of our rules and of criminal law are identified, they are investigated and prosecuted appropriately."