Lawyers for a Canadian businessman sentenced in Cuba to 15 years in prison say they will appeal the conviction.

Cy Tokmakjian, who owns the Ontario-based automotive company Tokmakjian Group, was sentenced last month on corruption-related charges that his family says are unfounded.

His lawyers say they will appeal to Cuba's Supreme Court despite "serious doubts and concerns that the results are pre-determined."

The lawyers had previously said they would hold off on further legal action if they could get assurances Tokmakjian would be released to serve his sentence in Canada.

The company's Cuban offices were raided in 2011 as the country launched an anti-graft drive that has swept up foreign business executives from at least five nations as well as government officials and dozens of Cuban employees at key state-run companies.

Tokmakjian, 74, was held for more than two years before being tried in June.

"Cy Tokmakjian was detained unfairly and has suffered enough," said Lorne Waldman, a Canadian human rights lawyer assisting the family.

"Cuba should allow Cy to return to Canada immediately. We will continue to work with the Canadian Government to help us win Cy's release," he said in a statement.

Tokmakjian's family has also expressed concerns about his health.