The Tim Hortons franchisee advisory board is slamming a group representing at least half of the brand's restaurant owners for publicly making complaints about their parent company Restaurant Brands International Inc.

In a letter to franchisees obtained by The Canadian Press, the board argues that the comments by the Great White North Franchisee Association criticizing the company in the media and to the federal government is corrosive and damaging to the Tim Hortons brand.

The GWNFA sparked a federal investigation when it wrote to Innovation Minister Navdeep Bains in April alleging the parent company had failed to live up to promises made under the Investment Canada Act in 2014, when RBI acquired Tim Hortons.

GWNFA has also attacked RBI in recent months for cost-cutting measures, cash register outages and a $700-million renovation plan to spruce up restaurants.

The board's letter says such moves have caused the public to watch and consider Tim Hortons more critically than before, exposing issues that might have gone overlooked previously.

Tim Hortons says it has nothing to say about the letter, but realizes it has work to do and welcomes conversations with the franchisees.