The superstar was part of a group of five, along with husband and manager Rene Angelil, who set up Nickel's in 1990. Now 17 of the 45 restaurants in the chain are at the centre of a £835,000 tax probe by the Canadian government.
Tax agents have launched a co-ordinated series of raids against Nickel's restaurants, including the chain's headquarters in Montreal, and search warrants were issued allowing the removal of papers and classified documents.
They are believed to relate to an investigation which began in March when seven Nickel's outlets were singled out for using illegal software which deletes cash sales from tills and enables users to under-report and evade taxes.
A spokesman for the chain said there were allegations of tax evasion but no official accusations. 'We are co-operating with Revenue Quebec in order to clarify and bring this investigation to a close,' the spokesman said.
Dion sold her shares in the restaurant in 1997 to her husband and manager Rene Angelil's cousin, but still acted as spokesman for the chain.
Cotton seedling freezes to death as Chang'e-4 shuts down for the Moon's 14-day lunar night
Fortnite easily out-earns PUBG, Assassin's Creed Odyssey and Red Dead Redemption 2 in 2018
Meteor showers as a service will be visible for about 100 kilometres in all directions
Saturn's rings only formed in the past 100 million years, suggests analysis of Cassini space probe data
New findings contradict conventional belief that Saturn's rings were formed along with the planet about 4.5 billion years ago