An investigation into a vodka bottle filled with water led to the discovery of a new form of tampering, CTV Toronto has learned.

The Liquor Control Board of Ontario (LCBO) told CTV Toronto's Paul Bliss that an investigation launched last week revealed a form of tampering that was previously undetected by inspectors.

The investigation began when a Pickering man found a plastic bottle of vodka he'd purchased at an LCBO was full of water.

The man returned the bottle to the store, and the LCBO launched a larger investigation, finding at least two locations where tampering was evident.

Toronto police were contacted, and are currently reviewing security camera video showing a man believed to be a suspect, though no further information has been provided.

The LCBO did not say exactly how the bottles had been tampered with, but said the method was new to inspectors.

The tampering appeared to only affect alcohol sold in plastic bottles.

For several months the LCBO has been adding anti-theft devices on high-theft items including bottles of vodka and rum.

The LCBO said that all plastic bottle products that are returned to the LCBO will no longer be offered for resale while they investigate. All LCBO employees will also be required to complete mandatory "refresher" training.

"We are also taking the appropriate steps to revise and strengthen our existing policies, procedures where necessary," LCBO spokesperson Keeley Rogers said.

With a report from CTV Toronto's Paul Bliss