Paul Desmarais Sr., the Canadian billionaire and long-time head of Power Corp. of Canada has died at the age of 86.

Desmarais’ family said he died at his estate northeast of Quebec City, surrounded by his relatives and loved ones. A private funeral service is being planned, and the family is expected to announce details of a public memorial service.

After getting his start in 1951 by reviving his family's bus company, a series of smart moves resulted in the creation of a holding company that in 1968 made a share-exchange offer with Power Corp. Desmarais took the helm at Power Corp. and served as chairman and CEO of company until his sons took over in 1996.

He remained director and chairman of the executive committee and the controlling shareholder until his death.

Under his leadership, Power Corp. became one of Canada's largest conglomerates, with holdings in insurance, transportation, paper, media and financial services.

By the time his sons took over, the company's assets had risen from $165 million to $2.7 billion, with its shares similarly increasing from $61 million to $2.6 billion – representing a compounded annual return of 16.4 per cent.

"Known for his vision, leadership and his innate sense of entrepreneurship and for his profound attachment to his country, Mr. Desmarais contributed greatly to turning Power Corporation into an international management and holding company with interests across North America, Europe and Asia," the company said in a statement.

Prime Minister Stephen Harper said Wednesday Desmarais was known for his leadership, integrity, global vision and “profound attachment to his country.”

“Mr. Desmarais will be remembered as a unique business leader who improved the lives of Canadians through the creation of jobs and through charitable endeavours,” Harper said in a statement.

During his time, Demarais became close with many of Canada’s most powerful politicians, including former prime ministers Brian Mulroney, Jean Chretien and Paul Martin.

Martin told CTV News Channel that Desmarais – a Franco-Ontarian born in 1927 in Sudbury, Ont., – had strong views on national unity and the role French Canadians could play in the country.

"He was a very strong Canadian and a very strong federalist," he said. "During the course of both referendums he spoke out on the issue. He loved his country, he loved Quebec and he loved Montreal," Martin added.

"He felt very strongly that Franco-Ontarians, Quebecors and Acadians – all had a strong role to play in Canada and the stronger role they played, the stronger Canada would be."

During his last annual meeting as Power Corp.’s chief executive in 1996, he celebrated his belief in Canadian unity.

"My profound attachment to Canada stems from the great liberty and freedom that my ancestors were able to enjoy in building their lives in a new country, the same liberty and freedom which allowed me as a young French-Canadian from Northern Ontario to realize his dream in building a business in all parts of Canada and abroad," he said.

Martin said the tycoon was a model businessman who had a very "strong global vision," and often travelled to Japan, the Middle East and China.

"He really did feel the pulse of the world."

Desmarais is credited with helping to open the door for Canadian businesses looking to set up in China, leading a commercial delegation to the country in 1978. He later became the founding chairman of the Canada China Business Council.

When Desmarais threw a housewarming party in 2003, the guests included two former U.S. presidents.

Nicolas Sarkozy once credited the business mogul with helping him become France’s president. Sarkozy returned the favour once he was in office, becoming an outspoken critic of Quebec independence.

Desmarais was regarded as a business partner and mentor to several of Canada’s top politicians.

After Desmarais took control of Power Corp in 1968, he convinced Martin – then a young lawyer with the company-- to stay on for another 13 years.

"He was a great motivator. He was a great example to follow," Martin said, noting that Desmarais' success was linked to his character. "Anyone who sat down with him knew his word was his bond."

Martin added that Desmarais always remained "down to earth" despite his enormous wealth – which Forbes pegged at $4.5 billion earlier this year.

"He was the kind of person you'd be absolutely delighted to spend an evening with, go fishing with or just chatting with," he said.

"I have never lost my love for the man or my respect for him."

A moment of silence was observed in the Quebec National Assembly Wednesday morning to mark Desmarais' death.

With files from The Canadian Press